Metal particle dispersion liquid, method for manufacturing metal particle dispersion liquid, method for manufacturing conductive-film-forming substrate, electronic device and electronic apparatus

ABSTRACT

A metal particle dispersion liquid comprises: a compound including a sulfur atom; metal particles whose diameter ranges from 1 to 100 nm and made of a material including a precious metal material; and a dispersion medium. The metal particles is covered by the compound.

This is a Continuation of application Ser. No. 11/373,909 filed Mar. 14,2006, which claims the benefit of Japanese Patent Application Nos.2005-080734 filed Mar. 18, 2005, 2005-080735 filed Mar. 18, 2005,2005-080736 filed Mar. 18, 2005, 2005-080737 filed Mar. 18, 2005 and2005-352761 filed Dec. 6, 2005. The disclosures of the priorapplications are hereby incorporated by reference herein in theirentirety.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a metal particle dispersion liquid, amethod for manufacturing a metal particle dispersion liquid, a methodfor manufacturing a conductive-film-forming substrate, an electronicdevice and an electronic apparatus.

2. Related Art

Conductive coatings or films are used for versatile applications, suchas electromagnetic shielding for cathode-ray tube monitors, infraredshielding for building materials and automobiles, static shielding forcellular phones and other electronic apparatuses, heat shielding forfogged glass, coating for resin to be conductive, for wiring included incircuit boards and integrated-circuit cards, and for through-holes andcircuits.

Examples of methods for making a conductive film include metal vacuumdeposition, chemical deposition and ion sputtering. These methods,however, require a complicated process in a vacuum or airtight systemand are costly and unsuitable for mass production.

To solve this problem, another method for making a conductive film hasbeen proposed lately that includes applying a metal particle dispersionliquid containing metal particles dispersed in a dispersion medium andheating and burning the dispersion liquid. JP-A-2001-325831 is anexample of related art. This method provides a conductive film easilyand economically with no process in a vacuum or airtight systemrequired.

The dispersion liquid usually includes a dispersing agent as an additiveto disperse metal particles. The dispersing agent needs to be stable inthe dispersion liquid but degradable to be removed quickly when thedispersion liquid turns to be a metal film after it is applied.

A highly stable dispersing agent that can increase dispersion is hard tobe removed. As a result, it requires a high-temperature burning processto turn the dispersion liquid into a metal film. Moreover, organiccomponents in the agent tend to remain in the metal film, making itdifficult to lower the resistance of the film. In contrast, a lessstable dispersing agent that can lower the resistance of the film ishard to maintain a sufficient dispersed state of the dispersion liquid.In particular, it is difficult to maintain a stable dispersed state fora long period of time.

SUMMARY

An advantage of the invention is to provide a metal particle dispersionliquid that is highly dispersed and stable in a dispersion medium andcan lower a burning temperature to turn the dispersion liquid into aconductive film, such as a wiring and conductive pattern, by usingultraviolet radiation together; also to provide a method for easily andsurely manufacturing the metal particle dispersion liquid; a method formanufacturing an efficient and reliable conductive-film-formingsubstrate; and an efficient and reliable electronic device andelectronic apparatus.

A metal particle dispersion liquid according to one aspect of theinvention includes: a compound having a sulfur atom, metal particleswhose diameter ranges from 1 to 100 nm and made of a material includinga precious metal material, and a dispersion medium. The metal particlesare covered by the compound.

Accordingly, the metal particles are highly dispersed and stable in thedispersion medium and can lower a burning temperature to turn thedispersion liquid into a conductive film, such as a wiring andconductive pattern, by using ultraviolet radiation together.

It is preferable that a molecule in the compound included in the metalparticle dispersion liquid contain a mercapto group and an ester group.

Accordingly, the metal particles are particularly highly dispersed andstable, and a conductive film made by using the dispersion liquid hasparticularly highly conductivity. Also, the burning temperature toprovide the conductive film can be further lowered. Moreover, theconductive film has sufficient conductivity even with ultravioletradiation under a milder condition.

It is preferable that the compound included in the metal particledispersion liquid be represented by HS(CH₂)_(n)COOR where n is aninteger from 1 to 5 and R represents one of a straight chain, branched,and cyclic alkyl group all of which having 1 to 8 carbon atoms.

Accordingly, the metal particles are particularly highly dispersed andstable, and a conductive film made by using the dispersion liquid hasparticularly highly conductivity. Also, the burning temperature toprovide the conductive film can be further lowered. Moreover, since thiscompound is highly reactive to ultraviolet rays, the conductive film hassufficient conductivity even with ultraviolet radiation under a mildercondition.

It is preferable that a molar ratio of the compound included in themetal particle dispersion liquid relative to atoms of the metalparticles range from 0.1 to 1.0.

Consequently, it is possible to desirably maintain a highly dispersedstate of the metal particles in the dispersion medium for a longerperiod of time. In addition, a dispersing agent used here can be removedwith a smaller amount of energy.

It is preferable that an average molecular weight of the compoundincluded in the metal particle dispersion liquid range from 106 to 260.

Consequently, it is possible to desirably maintain a highly dispersedstate of the metal particles in the dispersion medium for a longerperiod of time. In addition, the dispersing agent can be removed with asmaller amount of energy.

It is preferable that the compound included in the metal particledispersion liquid be a heterocyclic compound whose molecule contains asulfur atom.

Accordingly, the metal particles are particularly highly dispersed andstable, and a conductive film made by using the dispersion liquid hasparticularly highly conductivity. Also, the burning temperature toprovide the conductive film can be further lowered. Moreover, theconductive film has sufficient conductivity even with ultravioletradiation under a milder condition.

It is preferable that a molar ratio of the heterocyclic compoundincluded in the metal particle dispersion liquid relative to atoms ofthe metal particles range from 0.1 to 1.0.

Consequently, it is possible to desirably maintain a highly dispersedstate of the metal particles in the dispersion medium for a longerperiod of time. In addition, the dispersing agent can be removed with asmaller amount of energy.

It is preferable that a molecule in the heterocyclic compound includedin the metal particle dispersion liquid contain a nitrogen atom.

Consequently, it is possible to desirably maintain a highly dispersedstate of the metal particles in the dispersion medium for a longerperiod of time. In addition, the dispersing agent can be removed with asmaller amount of energy.

It is preferable that a circular structure in the heterocyclic compoundincluded in the metal particle dispersion liquid contain a nitrogen atomand/or a sulfur atom.

Consequently, by using the dispersion liquid to make a conductive film,for example, it is possible to surely prevent the heterocyclic compoundand its decomposed organic residue from remaining in the conductivefilm. Therefore, the conductive film has particularly high conductivity.

It is preferable that the heterocyclic compound included in the metalparticle dispersion liquid include a functional group that is bonded toa heterocycle in the heterocyclic compound and is able to be coordinatedto an atom of the metal particles.

Consequently, the metal particles are particularly highly dispersed. Byusing the metal particle dispersion liquid to make a conductive film,for example, it is possible to surely prevent the heterocyclic compoundand its decomposed organic residue from remaining in the conductivefilm. Therefore, the conductive film has particularly high conductivity.

It is preferable that an average molecular weight of the heterocycliccompound included in the metal particle dispersion liquid range from 80to 300.

Consequently, it is possible to desirably maintain a highly dispersedstate of the metal particles in the dispersion medium for a longerperiod of time. In addition, the dispersing agent can be removed with asmaller amount of energy.

It is preferable that the compound included in the metal particledispersion liquid be a thiol having 8 to 18 carbon atoms.

Accordingly, the metal particles are particularly highly dispersed andstable, and a conductive film made by using the dispersion liquid hasparticularly highly conductivity. Also, the burning temperature toprovide the conductive film can be further lowered. Moreover, theconductive film has sufficient conductivity even with ultravioletradiation under a milder condition.

It is preferable that the metal particle dispersion liquid satisfy0.05/A≦X≦1.00/A where an average diameter of the metal particles is A nmand a molar ratio of the thiol relative to atoms of the precious metalmaterial is X.

Consequently, it is possible to desirably maintain a highly dispersedstate of the metal particles in the dispersion medium for a longerperiod of time. In addition, the dispersing agent can be removed with asmaller amount of energy.

It is preferable that a peak half width in size distribution of themetal particles included in the metal particle dispersion liquid rangefrom 0.1 to 3.0 nm.

Accordingly, the metal particles are particularly highly dispersed evenif they account for a comparatively large portion of the metal particledispersion liquid. Furthermore, by using the dispersion liquid, forexample, it is possible to easily and surely make a conductive film witha minute pattern.

It is preferable that the metal particle dispersion liquid containbeta-ketoester in addition to the compound, the metal particles and thedispersion medium.

Accordingly, the metal particles are particularly highly dispersed andstable, and a conductive film made by using the dispersion liquid hasparticularly highly conductivity. Also, the burning temperature toprovide the conductive film can be further lowered. Moreover, theconductive film has sufficient conductivity even with ultravioletradiation under a milder condition.

It is preferable that the compound included in the metal particledispersion liquid be a thiol having 8 or more carbon atoms.

Consequently, it is possible to desirably maintain a highly dispersedstate of the metal particles in the dispersion medium for a longerperiod of time. In addition, the dispersing agent can be removed with asmaller amount of energy.

It is preferable that the beta-ketoester included in the metal particledispersion liquid have a structure represented by Chemical Formula 1.

R1: Fluorine-substituted alkyl group.R2: Straight chain, branched, or cyclic alkyl group having 1 to 8 carbonatoms.

Accordingly, the metal particles are particularly highly dispersed andstable, and a conductive film made by using the dispersion liquid hasparticularly highly conductivity. Also, the burning temperature toprovide the conductive film can be further lowered. Moreover, since thiscompound is highly reactive to ultraviolet rays, the conductive film hassufficient conductivity even with ultraviolet radiation under a mildercondition.

It is preferable that a molar ratio of the beta-ketoester included inthe metal particle dispersion liquid relative to atoms of the metalparticles range from 0.1 to 0.4.

Consequently, it is possible to desirably maintain a highly dispersedstate of the metal particles in the dispersion medium for a longerperiod of time. In addition, the dispersing agent can be removed with asmaller amount of energy.

It is preferable that an average molecular weight of the beta-ketoesterincluded in the metal particle dispersion liquid range from 140 to 400.

Consequently, it is possible to desirably maintain a highly dispersedstate of the metal particles in the dispersion medium for a longerperiod of time. In addition, the dispersing agent can be removed with asmaller amount of energy.

It is preferable that the precious metal material included in the metalparticle dispersion liquid be Ag.

Accordingly, the metal particles have particularly high conductivity.Furthermore, a conductive film made by using the dispersion liquid hasparticularly highly conductivity.

It is preferable that a content of the metal particles included in themetal particle dispersion liquid range from 10 to 60 wt %.

Accordingly, the metal particles are particularly highly dispersed inthe dispersion liquid.

A method for manufacturing the above-mentioned metal particle dispersionliquid according to another aspect of the invention includes: preparinga two-phase liquid including a precious metal salt to be the metalparticles, the compound, a water polar liquid, a nonpolar liquid that isinsoluble to the water polar liquid, and a phase-transfer catalyst;adding a reducing agent to the two-phase liquid to make the metalparticles covered by the compound; separating a nonpolar liquid phasecomposed of the nonpolar liquid together with the metal particles;mixing the separated nonpolar liquid phase and an alcohol having 1 to 3carbon atoms to make the metal particles precipitate; and dispersing theprecipitating metal particles in a liquid functioning as a dispersionmedium.

It is thus easily and surely manufacture the metal particle dispersionliquid in which the metal particles are highly dispersed and stable inthe dispersion medium and can lower a burning temperature to turn thedispersion liquid into a conductive film by using ultraviolet radiationtogether.

A method for manufacturing a conductive-film-forming substrate accordingto a yet another aspect of the invention includes the above-mentionedmethod for manufacturing the metal particle dispersion liquid.

This method provides an efficient and reliable conductive-film-formingsubstrate.

A method for manufacturing a conductive-film-forming substrate accordingto a still another aspect of the invention includes: depositing themetal particle dispersion liquid on a substrate to form an applicationfilm; and turning the application film into a conductive film. Turningthe application film into a conductive film includes: irradiating theapplication film with ultraviolet rays; and heating the applicationfilm.

This method provides an efficient and reliable conductive-film-formingsubstrate.

It is preferable that the heating be at 150 degrees Celsius or less inthe method for manufacturing a conductive-film-forming substrate.

Since a heating temperature can be thus kept low, it is possible toprovide a particularly reliable conductive-film-forming substrate.

An electronic device according to another aspect of the invention ismanufactured by the above-described method for manufacturing aconductive-film-forming substrate.

Accordingly, it is possible to provide an efficient and reliableelectronic device.

An electronic apparatus according to yet another aspect of the inventionincludes the above-described electronic device.

Accordingly, it is possible to provide an efficient and reliableelectronic apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is an exploded perspective view showing an electronic deviceaccording to one embodiment of the invention that is applied to atransmissive liquid crystal display.

FIG. 2 is a perspective view showing an electronic apparatus accordingto one embodiment of the invention that is applied to a mobile (ornotebook) personal computer.

FIG. 3 is a perspective view showing an electronic apparatus accordingto one embodiment of the invention that is applied to a cellular phoneor personal handyphone system.

FIG. 4 is a perspective view showing an electronic apparatus accordingto one embodiment of the invention that is applied to a digital stillcamera.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Preferred embodiments of the invention will be described hereinafterwith reference to the accompanying drawings.

Metal Particle Dispersion Liquid

A metal particle dispersion liquid according to preferred embodiments ofthe invention will be explained.

The metal particle dispersion liquid is composed of a compoundcontaining a sulfur atom (hereinafter referred to as the“sulfur-containing compound”) and a precious metal material. Thedispersion liquid includes metal particles (dispersed substance) whosediameters range from 1 to 100 nm and a dispersion medium. The metalparticles in the dispersion liquid are covered by the sulfur-containingcompound.

The term “metal particle dispersion liquid,” as used herein, refers to aliquid in which metal particles are dispersed and includes a colloidalliquid (solution).

First Embodiment

A metal particle dispersion liquid according to a first embodiment ofthe invention will now be described.

This metal particle dispersion liquid includes metal particles(dispersed substance) mainly made of a precious metal material. Thedispersion liquid also includes a dispersion medium and a compound whosemolecule contains a mercapto group and an ester group (hereinafterreferred to as the “mercapto-and-ester-group-containing compound”). Inother words, the dispersion liquid includes themercapto-and-ester-group-containing compound as the sulfur-containingcompound.

Metal Particles

The metal particles are mainly made of a precious metal material.

By using the metal particle dispersion liquid including the metalparticles mainly made of a precious metal material to make a conductivefilm, including a wiring or conductive pattern, for example, theconductive film becomes highly conductive. In particular, since preciousmetal materials generally have high chemical stability, it is possibleto maintain high conductivity for a long period of time. Precious metalmaterials also have high affinity for sulfur-containing compounds (e.g.the mercapto-and-ester-group-containing compound in the presentembodiment) as will be described in greater detail below. Consequently,the metal particles made of a precious metal material are highlydispersed in the dispersion liquid.

While any metal particles mainly made of a precious metal material canbe used here, the precious metal material may account for 90 wt % andmore in particle components preferably, or 95 wt % and more in thecomponents more preferably. Further preferably, the precious metalmaterial is practically the only component of the metal particles (e.g.accounting for 99.9 wt % and more). Consequently, the metal particlescan exhibit the above-described effects more markedly.

Examples of the precious metal material of the metal particles includeAg, Au, Pt, Pd, Ru, Rh, Os and Ir. Among them, Ag is preferably used asthe precious metal material of the metal particles. Since Ag hasparticularly high conductivity among the other precious metal materials,the conductive film made by using the dispersion liquid including themetal particles mainly made of Ag has particularly high conductivity.

The metal particles may be substantially made of a metal simplesubstance or a plurality of components like an alloy. Moreover, themetal particles may include other components than the precious metalmaterial (precious metal atoms), such as Cu, Al, Ni, Sn and Mg.

While the average diameter of the metal particles ranges from 1 to 100nm, it is preferably from 3 to 20 nm and more preferably from 3 to 7 nm.If the average diameter of the metal particles falls in theabove-mentioned range, the metal particles are particularly highlydispersed even if they account for a comparatively large portion of themetal particle dispersion liquid. Furthermore, by using the metalparticle dispersion liquid, for example, it is possible to easily andsurely make a conductive film with a minute pattern. If the averagediameter of the metal particles fails to reach the above-mentioned lowerlimit on one hand, the conductive film made by using the dispersionliquid may include many residual organic components depending on thecontent of the metal particles or of the sulfur-containing compound, forexample. As a result, the conductivity of the conductive film tents todecline and the metal particles in the dispersion liquid tend toaggregate, lowering the dispersion stability of the particles. On theother hand, if the average diameter of the metal particles exceeds theabove-mentioned upper limit, the dispersion stability of the metalparticles tend to decline depending on the content of the metalparticles or of the sulfur-containing compound, for example.Furthermore, if the average diameter exceeds the upper limit, it ispossibly difficult to make a conductive film with a required minutepattern by using the dispersion liquid, for example.

While the peak half width in size distribution of the metal particles isnot particularly limited, it may range from 0.1 to 3.0 nm preferably,and from 0.5 to 2.0 nm more preferably. If the peak half width in sizedistribution of the metal particles falls in the above-mentioned range,the metal particles are particularly highly dispersed even if theyaccounts for a comparatively large portion of the metal particledispersion liquid. Moreover, it is possible to reduce the variance ofeach particle's dispersion in the dispersion liquid. Therefore, thedispersion liquid becomes highly reliable and stable. Furthermore, byusing the dispersion liquid, for example, it is possible to easily andsurely make a conductive film with a minute pattern.

While the content of the metal particles in the dispersion liquid is notparticularly limited, it may range from 10 to 80 wt % preferably, from20 to 60 wt % more preferably, and from 40 to 60 wt % furtherpreferably. If the content of the metal particles falls in theabove-mentioned range, the metal particles can maintain a highlydispersed state in the dispersion liquid for a long period of time.Furthermore, by using the dispersion liquid, for example, it is possibleto efficiently make a conductive film with a small amount of thedispersion liquid.

Dispersion Medium

The dispersion medium functions as a medium to disperse the metalparticles in the dispersion liquid.

Examples of materials of the dispersion medium include: methanol,ethanol, isopropanol, butanol, octanol, ethylene glycol, diethyleneglycol, glycerin, terpineol (e.g. alpha-terpineol, beta-terpineol,gamma-terpineol) and other alcohols; methyl cellosolve, ethylcellosolve, phenyl cellosolve and other cellosolves; diethyl ether,tetrahydrofuran and other ethers; methyl acetate, ethyl acetate, butylacetate, ethyl formate and other esters; acetone, methyl ethyl ketone,diethyl ketone, methyl isobutyl ketone, methyl isopropyl ketone,cyclohexanone and other ketones; pentane, hexane, octane, tridecane andother aliphatic hydrocarbons (paraffinic hydrocarbons); cyclohexane,methylcyclohexane, tetralin, limonene and other alicyclic hydrocarbons;benzene, toluene, xylene, hexylbenzene, butylbenzene, octylbenzene,nonylbenzene, decylbenzene, undecylbenzene, dodecylbenzene,tridecylbenzene, tetradecylbenzen and other benzenes having a long-chainalkyl group (alkylbenzene derivatives); tetralin and other aromatichydrocarbons; methylene chloride, chloroform, carbon tetrachloride,1,2-dichloroethane and other halogenated hydrocarbons; pyridine,pyrazine, furan, pyrrole, thiophene, methylpyrrolidone and otheraromatic heterocycles; acetonitrile, propionitrile, acrylonitrile andother nitriles; N,N-dimethylformamide, N,N-dimethylacetamide and otheramides; and mineral spirits. One of them or two or more of them incombination can be used. Among them, the dispersion medium is preferablycomposed of a material whose molecule has a circular structure having anunsaturated bond, such as terpineol (e.g. alpha-terpineol,beta-terpineol, gamma-terpineol), tetralin, limonene, aromatichydrocarbons, and aromatic heterocycles. If the dispersion medium iscomposed of these materials, the metal particles are particularly highlydispersed.

Mercapto-and-Ester-Group-Containing Compound

As described above, the metal particle dispersion liquid according tothe present embodiment includes the mercapto-and-ester-group-containingcompound whose molecule contains a mercapto group and an ester group.

With the mercapto-and-ester-group-containing compound, the metalparticles are highly dispersed in the metal particle dispersion liquid.In particular, the inventor of the invention has found that the metalparticles are highly dispersed for a long period of time with noagitation required.

The inventor has also found that the metal particle dispersion liquidincluding the mercapto-and-ester-group-containing compound can bedesirably applied to making of a conductive film, such as metal wiring.Thus, by using the dispersion liquid to form a film in a predeterminedshape and then removing the dispersion medium and dispersing agent(mercapto-and-ester-group-containing compound) from the film to completea conductive film, a desirable pattern, particularly a minute pattern,can be formed easily and surely. Also, the conductive film has highconductivity.

This is because the mercapto-and-ester-group-containing compound as thedispersing agent has affinity for the metal particles, stability at roomtemperature, and degradability at low temperature. This compound as thedispersing agent is degradable to be removed quickly with heat at lowtemperature, while the dispersion liquid is stable. Moreover, since anester group reacts to ultraviolet rays, the dispersing agent isdegradable to be removed by burning at lower temperature together withultraviolet radiation.

If the dispersion liquid includes no mercapto-and-ester-group-containingcompound, the above-mentioned effects are not available. For example,the effects of the present embodiment are not available if a compoundhaving a mercapto group with no ester group or a compound having anester group with no mercapto group is used, or even if both of thesecompounds are used together.

While any mercapto-and-ester-group-containing compound can be used hereas long as its molecule has a mercapto group and an ester group, it maypreferably have a structure, for example, represented by the chemicalformula: HS(CH₂)_(n)COOR (n is an integer from 1 to 5, R represents astraight chain, branched, or cyclic alkyl group having 1 to 8 carbonatoms).

With the mercapto-and-ester-group-containing compound having thisstructure, the metal particles are particularly highly dispersed.Moreover, by using the dispersion liquid to make a conductive film, forexample, it is possible to surely prevent themercapto-and-ester-group-containing compound and its decomposed organicresidue from remaining in the conductive film. Therefore, the conductivefilm has particularly high conductivity.

While the average molecular weight of themercapto-and-ester-group-containing compound is not particularlylimited, it may range from 110 to 250 preferably, from 120 to 240 morepreferably, and from 130 to 215 further preferably. If the averagemolecular weight of the mercapto-and-ester-group-containing compoundfalls in the above-mentioned range, the metal particles are particularlyhighly dispersed. Moreover, by using the dispersion liquid to make aconductive film, for example, it is possible to surely prevent themercapto-and-ester-group-containing compound from remaining in theconductive film. Therefore, the conductive film has particularly highconductivity.

While the content of the mercapto-and-ester-group-containing compound inthe metal particle dispersion liquid is not particularly limited, itsmolar ratio relative to the metal atoms may range from 0.1 to 1.0preferably, from 0.3 to 1.0 more preferably, and from 0.3 to 0.5 furtherpreferably. If the content of the mercapto-and-ester-group-containingcompound falls in the above-mentioned range, the metal particles areparticularly highly dispersed even if they account for a comparativelylarge portion of the dispersion liquid. Moreover, by using thedispersion liquid to make a conductive film, for example, it is possibleto surely prevent the mercapto-and-ester-group-containing compound fromremaining in the conductive film. Therefore, the conductive film hasparticularly high conductivity.

Moreover, the metal particle dispersion liquid may include othercomponents. For example, the dispersion liquid may include otherdispersing agents than the mercapto-and-ester-group-containing compound.Examples of such dispersing agents include: trisodium citrate,tripotassium citrate, trilithium citrate, disodium malate, disodiumtartrate, sodium glycolate and other ionic compounds; hexanethiol,heptanethiol, octanethiol, nonanethiol, decanethiol, undecanethiol,dodecanethiol, tridecanethiol, tetradecanethiol, pentadecanethiol andother thiols; sodium dodecylbenzene sulfonate, sodium oleate,polyoxyethylene alkyl ether, perfluoroalkyl ethylene oxide adducts andother surface active agents; gelatin, gum arabic, albumin,polyethylenimine, polyvinyl celluloses, alkanethiols and other polymercompounds. One of them or two or more of them in combination can beused.

Second Embodiment

A metal particle dispersion liquid according to a second embodiment ofthe invention will now be described.

This metal particle dispersion liquid includes metal particles(dispersed substance) mainly made of a precious metal material. Thedispersion liquid also includes a dispersion medium and a heterocycliccompound whose molecule contains a nitrogen atom and a sulfur atom. Theheterocyclic compound serves as a dispersing agent. This means that themetal particle dispersion liquid according to the present embodimentincludes the heterocyclic compound whose molecule contains a sulfur atomas the sulfur-containing compound. In other words, the dispersion liquidincludes the heterocyclic compound whose molecule contains a sulfur atom(hereinafter simply referred to as the “heterocyclic compound”) servingas a dispersing agent.

Metal Particles

The metal particles according to the present embodiment are the same asthose in the first embodiment.

Since precious metal materials have high affinity for the heterocycliccompound as the sulfur-containing compound, the metal particles made ofa precious metal material are highly dispersed in the dispersion liquid.

Dispersion Medium

The dispersion medium according to the present embodiment is the same asthat in the first embodiment.

Heterocyclic Compound: Dispersing Agent

As mentioned above, the metal particle dispersion liquid according tothe present embodiment includes the heterocyclic compound serving as thedispersing agent.

With the heterocyclic compound, the metal particles are highly dispersedin the metal particle dispersion liquid. In particular, the inventor ofthe invention has discovered that the metal particles are highlydispersed for a long period of time with no agitation required.

The inventor has also discovered that the metal particle dispersionliquid including the heterocyclic compound can be desirably applied tomaking of a conductive film, such as metal wiring. Thus, by using thedispersion liquid to form a film in a predetermined shape and thenremoving the dispersion medium and dispersing agent from the film tocomplete a conductive film, a desirable pattern, particularly a minutepattern, can be formed easily and surely. Also, the conductive film hashigh conductivity.

This is because the heterocyclic compound as the dispersing agent hasaffinity for the metal particles, stability at room temperature, anddegradability at low temperature. This compound as the dispersing agentis degradable to be removed quickly with heat at low temperature, whilethe dispersion liquid is stable. Moreover, since the heterocycliccompound reacts to ultraviolet rays, the dispersing agent is degradableto be removed by burning at lower temperature together with ultravioletradiation.

If the dispersion liquid includes no heterocyclic compound, theabove-mentioned effects are not available. For example, the effects ofthe present embodiment are not available when using a sulfur-containingcompound containing no heterocycle or a heterocyclic compound containingno sulfur atom (e.g. a heterocyclic compound containing any of thefollowing as a heteroatom: oxygen, boron, aluminum, silicon,phosphorous, tin, arsenic and copper).

Any heterocyclic compound can be used here, as long as their moleculeshave a sulfur atom. For example, their heterocycles may have a sulfuratom (as a heteroatom included in the heterocycles). Otherwise, they mayhave a sulfur atom out of their heterocycles, which means they haveother atoms than sulfur as a heteroatom included in the heterocycles.

While any heterocyclic compound can be used as long as its molecule hasa sulfur atom, its molecule may preferably have a nitrogen atom.Consequently, it is possible to desirably maintain a highly dispersedstate of the metal particles in the dispersion medium for a longerperiod of time. In addition, the dispersing agent can be removed with asmaller amount of energy.

The heterocyclic compound preferably includes an unsaturated bond in itscircular structure. Consequently, by using the dispersion liquid to makea conductive film, for example, it is possible to surely prevent theheterocyclic compound and its decomposed organic residue from remainingin the conductive film. Therefore, the conductive film has particularlyhigh conductivity.

The heterocyclic compound preferably includes a nitrogen atom and/or asulfur atom in its circular structure. Consequently, by using thedispersion liquid to make a conductive film, for example, it is possibleto surely prevent the heterocyclic compound and its decomposed organicresidue from remaining in the conductive film. Therefore, the conductivefilm has particularly high conductivity.

In addition, the heterocyclic compound preferably includes a functionalgroup that is bonded to its heterocycle and is able to be coordinated toprecious metal atoms included in the metal particles. Consequently, themetal particles are particularly highly dispersed. By using thedispersion liquid to make a conductive film, for example, it is possibleto surely prevent the heterocyclic compound and its decomposed organicresidue from remaining in the conductive film. Therefore, the conductivefilm has particularly high conductivity. Examples of the functionalgroup include mercapto, amino, carboxyl and hydroxyl groups. Among them,mercapto groups are preferably used. If the heterocyclic compoundincludes a mercapto group bonded to its heterocycle, the above-describedeffects can be achieved more markedly.

As the heterocyclic compound, compounds having structures represented byChemical Formulae 2 to 8 can be used.

R1, R2 (each): Hydrogen, hydrocarbon having 1 to 3 carbon atoms,mercapto group, amino group, or hydroxyl group.

R3, R4, R5, R6, R7 (each): Hydrogen, hydrocarbon having 1 to 3 carbonatoms, mercapto group, amino group, or hydroxyl group.

R8, R9, R10: At least one of them is a mercapto group. Each of the restof them is hydrogen, a hydrocarbon having 1 to 3 carbon atoms, an aminogroup, or a hydroxyl group.

R11, R12, R13: At least one of them is a mercapto group. Each of therest of them is hydrogen, a hydrocarbon having 1 to 3 carbon atoms, anamino group, or a hydroxyl group.

R14, R15, R16, R17: At least one of them is a mercapto group. Each ofthe rest of them is hydrogen, a hydrocarbon having 1 to 3 carbon atoms,an amino group, or a hydroxyl group.

R18, R19, R20: At least one of them is a mercapto group. Each of therest of them is hydrogen, a hydrocarbon having 1 to 3 carbon atoms, anamino group, or a hydroxyl group.

R21, R22, R23: At least one of them is a mercapto group. Each of therest of them is hydrogen, a hydrocarbon having 1 to 3 carbon atoms, anamino group, or a hydroxyl group.

Among them, the compounds having the structures represented by ChemicalFormulae 2 and 3 are preferably used. With the heterocyclic compoundhaving any of these structures, the metal particles are particularlyhighly dispersed. By using the metal particle dispersion liquid to makea conductive film, for example, it is possible to surely prevent theheterocyclic compound and its decomposed organic residue from remainingin the conductive film. Therefore, the conductive film has particularlyhigh conductivity.

While the average molecular weight of the heterocyclic compound is notparticularly limited, it may range from 80 to 300 preferably, from 85 to128 more preferably, and from 90 to 120 further preferably. If theaverage molecular weight of the heterocyclic compound falls in theabove-mentioned range, the metal particles are particularly highlydispersed. Moreover, by using the dispersion liquid to make a conductivefilm, for example, it is possible to surely prevent the heterocycliccompound from remaining in the conductive film. Therefore, theconductive film has particularly high conductivity.

While the content of the heterocyclic compound in the metal particledispersion liquid is not particularly limited, its molar ratio relativeto the atoms of the metal particles may range from 0.1 to 1.0preferably, from 0.3 to 1.0 more preferably, and from 0.3 to 0.5 furtherpreferably. If the content of the heterocyclic compound falls in theabove-mentioned range, the metal particles are particularly highlydispersed even if they account for a comparatively large portion of themetal particle dispersion liquid. Moreover, by using the dispersionliquid to make a conductive film, for example, it is possible to surelyprevent the heterocyclic compound from remaining in the conductive film.Therefore, the conductive film has particularly high conductivity.

Moreover, the metal particle dispersion liquid may include othercomponents. For example, the dispersion liquid may include otherdispersing agents than the heterocyclic compound. Examples of suchdispersing agents include: trisodium citrate, tripotassium citrate,trilithium citrate, disodium malate, disodium tartrate, sodium glycolateand other ionic compounds; hexanethiol, heptanethiol, octanethiol,nonanethiol, decanethiol, undecanethiol, dodecanethiol, tridecanethiol,tetradecanethiol, pentadecanethiol and other thiols; sodiumdodecylbenzene sulfonate, sodium oleate, polyoxyethylene alkyl ether,perfluoroalkyl ethylene oxide adducts and other surface active agents;gelatin, gum arabic, albumin, polyethylenimine, polyvinyl celluloses,alkanethiols and other polymer compounds; and themercapto-and-ester-group-containing compound described in the firstembodiment. One of them or two or more of them in combination can beused.

Third Embodiment

A metal particle dispersion liquid according to a third embodiment ofthe invention will now be described.

This metal particle dispersion liquid includes metal particles(dispersed substance) mainly made of a precious metal material. Thedispersion liquid also includes a dispersion medium and a thiol having 8to 18 carbon atoms (hereinafter also simply referred to as the “thiol”).In other words, the metal particle dispersion liquid according to thepresent embodiment includes the thiol having 8 to 18 carbon atoms as thesulfur-containing compound.

Metal Particles

The metal particles according to the present embodiment are the same asthose in the first embodiment.

Since precious metal materials have high affinity for the thiol as thesulfur-containing compound, the metal particles made of a precious metalmaterial are highly dispersed in the dispersion liquid.

Dispersion Medium

The dispersion medium according to the present embodiment is the same asthat in the first embodiment.

Thiol

As mentioned above, the metal particle dispersion liquid according tothe present embodiment includes the thiol having 8 to 18 carbon atoms asa dispersing agent.

Examples of the thiol include: octanethiol (e.g. 1-octanethiol,2-octanethiol), nonanethiol, decanethiol, undecanethiol, dodecanethiol,tridecanethiol, tetradecanethiol, pentadecanethiol, hexadecanethiol,heptadecanethiol, octadecanethiol and compounds obtained by introducinga substituent group (e.g. a halogen group or two or more mercaptogroups) into molecules of any of the thiols. One of them or two or moreof them in combination can be used. The thiol having 8 to 18 carbonatoms may have two or more mercapto groups in its molecule, for example.

With the thiol having any of these structures, the metal particles areparticularly highly dispersed in the dispersion liquid. Having paidattention to the relationship between the size of the metal particlesand the content of the dispersing agent required to desirably dispersethe metal particles, the inventor of the invention has discovered thatthe content of the thiol that satisfies a certain relation with theaverage diameter of the metal particles can highly disperse the metalparticles in the dispersion liquid. At the same time, by using thedispersion liquid to make a conductive film as described below(particularly when using ultraviolet radiation), for example, it ispossible to effectively prevent the thiol (dispersing agent) fromremaining in the conductive film even with processing under acomparatively mild condition (e.g. at comparatively low temperature).Therefore, the conductive film has particularly high conductivity.

The certain relation according to the present embodiment is representedby the following formula: 0.05/A≦X≦1.00/A where the average diameter ofthe metal particles is A nm and the content of the thiol, i.e. its molarratio relative to atoms of the precious metal material, in thedispersion liquid is X. When the formula is satisfied, theabove-mentioned effects can be achieved. If the content X fails to reachthe lower limit on one hand, the above-mentioned effects are notavailable and the metal particles are not desirably dispersed. On theother, if the dispersion liquid is used to make a conductive film asdescribed below for example, with the content X exceeding the upperlimit, the thiol will remain in the conductive film. As a result, theconductive film has poor conductivity.

The formula is based on the following idea. When the average diameter ofthe metal particles is 5 nm, the molar ratio of the thiol relative tothe metal atoms needs to be 0.01 to 0.20 in order to achieve theabove-mentioned effects. The amount of the thiol falling in this rangeis not large enough to cover and protect the surface of every metalparticle (a molar ratio of about 0.30 at least is required to cover thesurface of every metal particle whose diameter is 5 nm), but issufficient to disperse the metal particles desirably. Thus the inventorof the invention has found that the dispersion liquid including thethiol of the amount within the range can provide both dispersionstability in and degradability at low temperature (particularly whenusing ultraviolet radiation together).

If the diameter of the metal particles increases in the dispersionliquid with the total number of the metal atoms unchanged, the surfacearea of each metal particle increases but the total amount of the metalparticles decreases to a larger extent. As a result, the amount of thethiol, which is required to cover the surface of the metal particles tothe same extent that it covers the original metal particles, declines ininverse proportion to the diameter of the metal particles. The inventorof the invention has set the above formula based on the fact that thesame effects as the molar ratio of 0.01 to 0.20 with the diameter of 5nm can be achieved when the molar ratio falls in the range from 0.01*5/Ato 0.20*5/A with the diameter of A in inverse proportion to the diameterof the metal particles (when their diameters range from 1 to 100 nm). Itis understood that the formula is satisfied generally as for particlesmade of precious metal materials, such as other precious metal materialsthan Ag, and precious metal alloys, since the diameter of a particlemade of the same number of atoms is almost the same.

According to the present embodiment, the average diameter (A nm) of themetal particles and the content (X) of the thiol, i.e. its molar ratiorelative to atoms of the precious metal, in the dispersion liquidsatisfy the formula: 0.05/A≦X≦1.00/A as mentioned above. Preferably,they may satisfy the formula: 0.10/A≦X≦1.00/A. More preferably, they maysatisfy the formula: 0.20/A≦X≦0.50/A. When the formula is satisfied, theabove-described effects can be achieved more markedly.

The above-mentioned effects are available only when the thiol having 8to 18 carbon atoms is used and not available when other dispersingagents than the thiol having 8 to 18 carbon atoms are used. In otherwords, when thiols having 7 or less or having 19 or more carbon atoms orother dispersing agents than thiols are used, the above-mentionedeffects are not available even if such dispersing agents and the metalparticles satisfy the above formula.

While the content of the thiol having 8 to 18 carbon atoms (molar ratiorelative to atoms of the precious metal) in the metal particledispersion liquid is not particularly limited, it may range from 0.001to 0.500 preferably, and from 0.010 to 0.200 more preferably. If thecontent of the thiol having 8 to 18 carbon atoms falls in theabove-mentioned range, the metal particles are particularly highlydispersed even if they account for a comparatively large portion of themetal particle dispersion liquid. At the same time, by using thedispersion liquid to make a conductive film, it is possible to surelyprevent the thiol from remaining in the conductive film. Therefore, theconductive film has particularly high conductivity.

Moreover, the metal particle dispersion liquid may include othercomponents. For example, the dispersion liquid may include otherdispersing agents than the thiol having 8 to 18 carbon atoms. Examplesof such dispersing agents include: trisodium citrate, tripotassiumcitrate, trilithium citrate, disodium malate, disodium tartrate, sodiumglycolate and other ionic compounds; butanethiol, pentanethiol,hexanethiol, heptanethiol and other thiols having 7 or less carbonatoms; nonadecanethiol, icosanethiol and other thiols having 19 or morecarbon atoms; sodium dodecylbenzene sulfonate, sodium oleate,polyoxyethylene alkyl ether, perfluoroalkyl ethylene oxide adducts andother surface active agents; gelatin, gum arabic, albumin,polyethylenimine, polyvinyl celluloses, alkanethiols and other polymercompounds; and the mercapto-and-ester-group-containing compounddescribed in the first embodiment; and the heterocyclic compounddescribed in the second embodiment. One of them or two or more of themin combination can be used. When such a dispersing agent other than thethiol having 8 to 18 carbon atoms is contained, the content of thisagent (its molar ratio relative to the thiol) in the metal particledispersion liquid is preferably 0.5 or less.

Fourth Embodiment

A metal particle dispersion liquid according to a fourth embodiment ofthe invention will now be described.

This metal particle dispersion liquid includes metal particles(dispersed substance) mainly made of a precious metal material. Thedispersion liquid also includes a dispersion medium, a sulfur-containingcompound as a dispersing agent, and beta-ketoester as a dispersing aid.In other words, the dispersion liquid according to the presentembodiment includes beta-ketoester in addition to the sulfur-containingcompound.

Metal Particles

The metal particles according to the present embodiment are the same asthose in the first embodiment.

Since precious metal materials have high affinity for beta-ketoester,which will be described in greater detail later, the metal particlesmade of a precious metal material are highly dispersed in the dispersionliquid.

Dispersion Medium

The dispersion medium according to the present embodiment is the same asthat in the first embodiment.

Dispersing Agent and Beta-Ketoester

As mentioned above, the metal particle dispersion liquid according tothe present embodiment includes the sulfur-containing compound as thedispersing agent and beta-ketoester as the dispersing aid.

With the dispersing agent and the beta-ketoester, the metal particlesare highly dispersed in the metal particle dispersion liquid. Inparticular, the inventor of the invention has discovered that the metalparticles are highly dispersed for a long period of time with noagitation required.

The inventor has also discovered that the metal particle dispersionliquid including the dispersing agent and the beta-ketoester can bedesirably applied to making of a conductive film, such as metal wiring.Thus, by using the dispersion liquid to form a film in a predeterminedshape and then removing the dispersion medium from the film to completea conductive film, a desirable pattern, particularly a minute pattern,can be formed easily and surely. Also, the conductive film has highconductivity.

This is because the dispersing agent and the beta-ketoester functionsynergistically. Compared to the use of the dispersing agent alone (nobeta-ketoester used), the metal particles are highly dispersed even ifthe content of the dispersing agent (the total content of the dispersingagent and the beta-ketoester as the dispersing aid) is significantlylow. Accordingly, the dispersing agent (and the beta-ketoester) can beeasily and surely removed to complete a conductive film. Therefore, itis possible to make the conductive film have particularly highconductivity.

The above-mentioned effects are not available if the dispersing agentand the beta-ketoester are not used together. For example, the effectsof the present embodiment are not available if the metal particledispersion liquid includes the dispersing agent but no beta-ketoester,or includes the beta-ketoester but no dispersing agent.

Dispersing Agent

The dispersing agent mainly functions to disperse the metal particles.

Examples of the dispersing agent include: hexanethiol, heptanethiol,octanethiol, nonanethiol, decanethiol, undecanethiol, dodecanethiol,tridecanethiol, tetradecanethiol, pentadecanethiol and other thiols;sodium dodecylbenzene sulfonate and other surface active agents;gelatin, gum arabic, polyvinyl celluloses, alkanethiols and otherpolymer compounds. One of them or two or more of them in combination canbe used.

Among them, the thiol having 8 or more carbon atoms is preferably usedas the dispersing agent. Accordingly, the dispersing agent and thebeta-ketoester function in a synergistic manner more effectively,thereby the metal particles are particularly highly dispersed. Moreover,by using the dispersion liquid to make a conductive film, for example,it is possible to surely prevent the dispersing agent and thebeta-ketoester etc. from remaining in the conductive film. Therefore,the conductive film has particularly high conductivity. Examples of thethiol having 8 or more carbon atoms include: octanethiol (e.g.1-octanethiol, 2-octanethiol), nonanethiol, decanethiol, undecanethiol,dodecanethiol, tridecanethiol, tetradecanethiol, pentadecanethiol andcompounds obtained by introducing a substituent group (e.g. a halogengroup or two or more mercapto groups) into molecules of any of thethiols. One of them or two or more of them in combination can be used.The thiol having 8 or more carbon atoms may have two or more mercaptogroups in its molecule, for example.

While the average molecular weight of the thiol having 8 or more carbonatoms (hereinafter also simply referred to as the “thiol”) is notparticularly limited, it may range from 146 to 300 preferably, from 160to 272 more preferably, and from 188 to 230 further preferably. If theaverage molecular weight of the thiol falls in the above-mentionedrange, the metal particles are particularly highly dispersed. Moreover,by using the dispersion liquid to make a conductive film, for example,it is possible to surely prevent the thiol from remaining in theconductive film. Therefore, the conductive film has particularly highconductivity.

While the content of the thiol in the dispersion liquid is notparticularly limited, its molar ratio relative to the atoms of the metalparticles may range from 0.1 to 0.4 preferably, and from 0.2 to 0.3 morepreferably. If the content of the thiol in the dispersion liquid fallsin the above-mentioned range, the metal particles are particularlyhighly dispersed even if they account for a comparatively large portionof the metal particle dispersion liquid. Moreover, by using thedispersion liquid to make a conductive film, for example, it is possibleto surely prevent the thiol etc. from remaining in the conductive film.Therefore, the conductive film has particularly high conductivity.

Furthermore, the mercapto-and-ester-group-containing compound describedin the first embodiment and the heterocyclic compound described in thesecond embodiment may be used as the dispersing agent here. Accordingly,the above-described effects and the synergetic effects of using thedispersing agent and the beta-ketoester together can be achieved moreeffectively

Beta-Ketoester

While any beta-ketoester can be used here as long as it has a keto groupin its beta position, it may preferably has a structure represented byChemical Formula 9.

R1: Fluorine-substituted alkyl group.R2: Straight chain, branched, or cyclic alkyl group having 1 to 8 carbonatoms.

With the beta-ketoester having this structure, the metal particles areparticularly highly dispersed. Moreover, by using the dispersion liquidto make a conductive film, for example, it is possible to surely preventthe beta-ketoester etc. from remaining in the conductive film.Therefore, the conductive film has particularly high conductivity. It isalso possible to produce the beta-ketoester easily with commercialreagents.

While the average molecular weight of the beta-ketoester is notparticularly limited, it may range from 140 to 400 preferably, from 160to 370 more preferably, and from 180 to 330 further preferably. If theaverage molecular weight of the beta-ketoester falls in theabove-mentioned range, the metal particles are particularly highlydispersed. Furthermore, by using the dispersion liquid to make aconductive film, for example, it is possible to surely prevent thebeta-ketoester etc. from remaining in the conductive film. Therefore,the conductive film has particularly high conductivity.

The content of the beta-ketoester, that is, its molar ratio relative tothe metal atoms, ranges from 0.1 to 1.0 preferably, from 0.3 to 1.0 morepreferably, and from 0.3 to 0.4 further preferably. Accordingly, themetal particles are particularly highly dispersed even if they accountfor a comparatively large portion of the metal particle dispersionliquid. Moreover, by using the dispersion liquid to make a conductivefilm, for example, it is possible to surely prevent the thiol and thebeta-ketoester etc. from remaining in the conductive film. Therefore,the conductive film has particularly high conductivity.

Method for Manufacturing (Preparing) Metal Particle Dispersion Liquid

While the metal particle dispersion liquid may be manufactured(prepared) by any method, one method includes the following, forexample: preparing a two-phase liquid including a precious metal salt tobe metal particles, a sulfur-containing compound, a water polar liquid,a nonpolar liquid that is substantially insoluble to the water polarliquid, and a phase-transfer catalyst; adding a reducing agent to thetwo-phase liquid to make the metal particles covered by thesulfur-containing compound; separating a nonpolar liquid phase composedof the nonpolar liquid together with the metal particles; mixing theseparated nonpolar liquid phase and an alcohol having 1 to 3 carbonatoms to make the metal particles precipitate; and dispersing theprecipitating metal particles in a liquid functioning as a dispersionmedium. To prepare the two-phase liquid, beta-ketoester can be used asneeded. The method for manufacturing (preparing) the metal particledispersion liquid will be described in greater detail below.

First Method

First, the metal salt of an element to be the metal particles isobtained by reducing the two-phase liquid composed of the water polarliquid (including the phase-transfer catalyst and the sulfur-containingcompound) and the nonpolar liquid (substantially insoluble to the waterpolar liquid) with the reducing agent. Thus the metal particlesprotected by the sulfur-containing compound as a dispersing agent areformed. The reduction helped by the reducing agent is preferably carriedout by agitating the two-phase liquid. Accordingly, the metal particleswith a small variance in their diameters are formed.

The above-mentioned process can be carried out by mixing the two-phaseliquid including the metal salt, and the reducing agent. Otherwise, itcan be carried out by mixing the water polar liquid including the metalsalt, and the nonpolar liquid including the reducing agent.

Examples of the metal salt include: silver nitrate, silver sulfate,silver chloride, silver oxide, silver acetate, silver nitrite, silverchlorate, silver sulfide and other silver salts; chlorauric acid,potassium chloroaurate, sodium chloroaurate and other gold salts;chloroplatinic acid, platinum chloride, platinum oxide, potassiumplatinum chloride and other platinum salts; palladium nitrate, palladiumacetate, palladium chloride, palladium oxide, palladium sulfate andother palladium salts; and other types of precious metal salts. One ofthem or two or more of them in combination can be used.

Water or polar liquids soluble in water (e.g. a liquid with a solubilityof 30 grams or more in 100-gram water at 25 degrees Celsius) can be usedas the water polar liquid. Examples of such liquids include: water,methanol, ethanol and other alcohols, acetone and other ketones.

Any liquid that is substantially insoluble to the water polar liquid(e.g. a liquid with a solubility of 1 gram or less in 100-gram water at25 degrees Celsius) can be used as the nonpolar liquid. Examples of suchliquids include: methyl acetate, ethyl acetate, butyl acetate, ethylformate and other esters; pentane, hexane, octane, tridecane and otheraliphatic hydrocarbons (paraffinic hydrocarbons); cyclohexane,methylcyclohexane, tetralin, limonene and other alicyclic hydrocarbons;benzene, toluene, xylene, hexylbenzene, butylbenzene, octylbenzene,nonylbenzene, decylbenzene, undecylbenzene, dodecylbenzene,tridecylbenzene, tetradecylbenzen and other benzenes having a long-chainalkyl group (alkylbenzene derivatives); tetralin and other aromatichydrocarbons; methylene chloride, chloroform, carbon tetrachloride,1,2-dichloroethane and other halogenated hydrocarbons. One of them ortwo or more of them in combination can be used.

Examples of the reducing agent include: dimethylaminoethanol,methyldiethanolamine, triethanolamine, phenidone, hydrazine and otheramine compounds; sodium borohydroxide, hydrogen iodide, hydrogen gas andother hydrogen compounds; carbon monoxide, sulfurous acid and otheroxides; ferrous sulfate, iron chloride, iron fumarate, iron lactate,iron oxalate, iron sulfide, tin acetate, tin chloride, tin diphosphate,tin oxalate, tin oxide, tin sulfate and other low-valent metal salts;formaldehyde, hydroquinone, pyrogallol, tannin, tannic acid, salicylicacid, D-glucose and other sugars and other organic compounds. One ofthem or two or more of them in combination can be used. When any of thereducing agents is used, the reduction reaction may be promoted withlight or heat.

Subsequently, the nonpolar liquid phase in which the metal particlesprotected by the dispersing agent (sulfur-containing compound) isseparated. Then the alcohol having 1 to 3 carbon atoms is added to theseparated nonpolar liquid phase so as to lower the dispersion of themetal particles and make the metal particles protected by the dispersingagent precipitate. If necessary, the precipitating particles may bebrought out and cleaned with the alcohol again to remove unnecessaryresidues of the reducing agent and the phase-transfer catalyst. Cleaningmay be carried out for multiple times. The metal particles thus producedhave a small variance in their diameters and few impurities.

Examples of the alcohol having 1 to 3 carbon atoms include methanol,ethanol, and propanol (n-propanol, isopropanol).

Then, the precipitating metal particles are dispersed in a liquidfunctioning as the dispersion medium, which completes the metal particledispersion liquid.

Second Method

Here is another method for manufacturing the metal particle dispersionliquid.

First, the metal salt of an element to be the metal particles, a liquidcontaining the alcohol having 1 to 3 carbon atoms, and thesulfur-containing compound are mixed. Next, the reducing agent is addedto this reaction liquid and the liquid is then agitated.

The reaction liquid is left for a certain period of time to make themetal particles precipitate. The period is not particularly limited, andmay be 5 minutes to 20 hours, for example.

Subsequently, the precipitating metal particles are dispersed in aliquid functioning as the dispersion medium, which completes the metalparticle dispersion liquid.

The above-described methods easily and surely provide the metal particledispersion liquid in which the metal particles are highly dispersed.Furthermore, it is possible to easily and surely manufacture the metalparticle dispersion liquid that can be desirably applied to making of aconductive film, such as metal wiring.

The metal particle dispersion liquid can be used for any purpose. Forexample, it can be applied to making of ornaments (forming of ornamentalpatterns) and of conductive films (forming of wiring patterns). A methodfor making a conductive film and a conductive film made by the methodaccording to a still another embodiment will now be described.

Conductive Film and Method for Making Conductive Film

A conductive film according to the present embodiment is manufactured byusing the above-described metal particle dispersion liquid.

Specifically, the conductive film is manufactured as follows, forexample.

First, the metal particle dispersion liquid is deposited on a substrateon which the conductive film will be provided.

Examples of methods for depositing the metal particle dispersion liquid(film-forming methods) may include, but not be limited to, spin coating,dip coating, spray coating, roll coating, screen printing and dropletdischarge methods (e.g. inkjet printing). Among them, the dropletdischarge methods are preferably used, since they can provide a filmhaving a minute pattern easily and accurately.

Substantially, the dispersion medium and the dispersing agent thatcovers and protects the surface of the metal particles are removed fromthe film that has provided in a predetermined shape, which completes theconductive film.

While any method can be used here to remove the dispersion medium andthe dispersing agent, heating (burning) is preferably carried out forthis purpose. Accordingly, interparticle bonding (diffusion) proceeds,thereby the conductive film has particularly high conductivity andreliability.

While the heating temperature is not particularly limited, it may be 300degrees Celsius or lower preferably, 200 degrees Celsius or lower morepreferably, and 150 degrees Celsius or lower further preferably.

In addition to the heating, ultraviolet radiation is preferably carriedout. Accordingly, the dispersing agent (e.g. the sulfur-containingcompound) is efficiently removed at comparatively low temperatures,thereby providing the conductive film in which interparticle bonding(diffusion) has proceeded sufficiently. The conductive film thusproduced has particularly high conductivity.

While the heating temperature when the ultraviolet radiation is carriedout is not particularly limited, it may be 250 degrees Celsius or lowerpreferably, from 100 to 200 degrees Celsius more preferably, and from120 to 180 degrees Celsius further preferably.

While heating methods when the ultraviolet radiation is carried out arenot particularly limited, infrared radiation may be used preferably.Accordingly, the film can be selectively heated, while the substrate isprevented from being heated.

While any ultraviolet rays can be used here as long as they have 400-nmor less wavelength components, they may mainly have 1- to 380-nmwavelength components preferably. Consequently, the ultravioletradiation can exhibit the above-described effects more markedly. Inparticular, when the mercapto-and-ester-group-containing compounddescribed in the first embodiment or the heterocyclic compound describedin the second embodiment is used as the sulfur-containing compound, orthe beta-ketoester described in the fourth embodiment is used togetherwith the dispersing agent (sulfur-containing compound), the ultravioletrays may mainly have 180- to 360-nm wavelength components preferably,and 240- to 260-nm wavelength components more preferably. When the thiolhaving 8 to 18 carbon atoms described in the third embodiment is used asthe sulfur-containing compound, the ultraviolet rays may mainly have 30-to 360-nm wavelength components preferably, and 60- to 260-nm wavelengthcomponents more preferably. Consequently, the ultraviolet radiation canexhibit the above-described effects more markedly.

While the radiation intensity of the ultraviolet rays is notparticularly limited, it may be 0.5 mW/cm² or higher preferably, 2.0mW/cm² or higher more preferably, and 10.0 mW/cm² or higher furtherpreferably.

While the radiation time of the ultraviolet rays is not particularlylimited, it may range from 1 second to 5 hours preferably.

The radiation of the ultraviolet rays and the heating may be carried outeither simultaneously or non-simultaneously (the radiation may becarried out before or after the heating).

The conductive film thus produced has particularly high conductivity.

In this case, the conductive film has an electrical resistance(resistivity) of 10 μΩcm or less preferably, and of 5 μΩcm or less morepreferably.

Electronic Device

An electronic device according to yet another embodiment of theinvention will now be described. The electronic device has theabove-described conductive film and is applied to an active-matrixtransmissive liquid crystal display (LCD), for example.

FIG. 1 is an exploded perspective view showing the electronic deviceaccording to the present embodiment of the invention that is applied toa transmissive LCD.

In FIG. 1, part of the members of the display is omitted to simplify thedescription. The upper side of the drawing is hereinafter referred to asthe “top” and the lower side of the drawing as the “bottom”.

Referring to FIG. 1, this transmissive LCD (hereinafter simply referredto as the “LCD”) 100 includes a liquid crystal panel (display panel) 200and a backlight (light source) 600.

The LCD 100 displays images (information) by transmitting light from thebacklight 600 to the liquid crystal panel 200.

The liquid crystal panel 200 includes a first substrate 220 and a secondsubstrate 230 that are placed face to face with each other. Providedbetween the first substrate 220 and the second substrate 230 is asealing material (not shown) that surrounds a display area.

Between the first substrate 220 and the second substrate 230, a liquidcrystal layer 240 is interposed.

Both of the first substrate 220 and the second substrate 230 are made ofa glass material, for example.

The first substrate 220 is provided on its top surface 221 (on theliquid crystal layer 240 side) with a plurality of pixel electrodes 223arranged in a matrix and a signal electrode 224 extending in the Xdirection. Each of the pixel electrodes 223 in a column are coupled toone signal electrode 224 via a switching element 222.

The switching element 222 is a thin-film diode (TFD) or a thin-filmtransistor (TFT), for example.

For example, if the switching element 222 is a TFD, a metal layer 229 isprovided on an extraction part 228 extracted from the signal electrode224 with an insulating film therebetween. Thus the metal layer 229 iscoupled to the pixel electrodes 223. Since the switching element 222 hasa metal-insulator-metal sandwich structure, it has diode switchingcharacteristics in the positive and negative directions.

The signal electrode 224 and the extraction part 228 include any of theabove-described conductive films.

Provided on the bottom surface of the first substrate 220 is apolarizing plate 225.

The second substrate 230 is provided on its bottom surface 231 (on theliquid crystal layer 240 side) with a plurality of strip scanningelectrodes 232. The scanning electrodes 232 are arranged almost inparallel with each other at predetermined intervals along the Ydirection, which is almost orthogonal to the signal electrode 224. Also,the scanning electrodes 232 are arranged to be opposed to the pixelelectrodes 223.

Each overlapping area of the pixel electrodes 223 and the scanningelectrodes 232 (and its peripheral area) functions as a pixel. Chargeand discharge between the electrodes drive the liquid crystal of theliquid crystal layer 240, that is to say, change the orientation of theliquid crystal.

Provided on the bottom surface of the scanning electrodes 232 are red(R), green (G) and blue (B) color layers (color filters) 233. The colorfilters 232 are partitioned by a black matrix 234.

Provided on the top surface of the second substrate 230 is anotherpolarizing plate 235 whose polarizing axis differs from that of thepolarizing plate 225.

With this liquid crystal panel 200, light from the backlight 600 ispolarized by the polarizing plate 225 and enters the liquid crystallayer 240 through the first substrate 220 and each of the pixelelectrodes 223. The intensity of the light that has entered the liquidcrystal layer 240 is modulated by the liquid crystal whose orientationis controlled for each pixel. Subsequently, the light passes through thecolor layers 233, the scanning electrodes 232 and the second substrate230. The light is then polarized by the polarizing plate 235 and exitsto the outside. Accordingly, both moving and still colored images, suchas characters, figures and graphics, are viewed with the LCD 100 fromthe side of the second substrate 230 opposite to the liquid crystallayer 240 side.

The LCD 100 can be used as displays included in various electronicapparatuses.

Note that the electronic device according to the present embodiment isapplicable not only to the LCD described above, but also to organic andinorganic electroluminescent devices, organic or inorganic TFTs,electrophoretic displays and noncontact integrated circuit cards, forexample. This means that the above-described conductive films areapplicable to electrodes and wiring included in these electronicdevices.

Electronic Apparatus

Electronic apparatuses including the above-mentioned electronic device(LCD) will now be described.

FIG. 2 is a perspective view showing an electronic apparatus accordingto another embodiment of the invention that is applied to a mobile (ornotebook) personal computer.

Referring to this drawing, this personal computer 1100 includes a body1104 having a keyboard 1102, and a display unit 1106. The display unit1106 is supported rotatably to the body 1104 with a hinge structure.

In the personal computer 1100, the display unit 1106 includes the LCD100 (electrooptical device).

FIG. 3 is a perspective view showing an electronic apparatus accordingto a yet another embodiment of the invention that is applied to acellular phone or personal handyphone system.

Referring to this drawing, this cellular phone 1200 includes the LCD 100(electrooptical device), a plurality of operation buttons 1202, anearpiece 1204 and a mouthpiece 1206.

FIG. 4 is a perspective view showing an electronic apparatus accordingto a still another embodiment of the invention that is applied to adigital still camera. This drawing also simply shows coupling toexternal apparatuses.

This digital still camera 1300 includes a case (body) 1302 and the LCD100 as a display on the back side of the case 1302. The LCD 100functions as a finder to display a photographic subject as an electronicimage by providing a display based on an imaging signal from acharge-coupled device (CCD).

Provided inside the case is a circuit board 1308. The circuit board 1308has a memory that is capable of storing the imaging signal.

The camera also includes a light-receiving unit 1304 including anoptical lens (imaging optical system) and the CCD on the front side (onthe back side of the drawing) of the case 1302.

When a photographer views an image of a photographic subject displayedon the LCD 100 and presses a shutter button 1306, the imaging signal inthe CCD at the moment is transferred to and stored in the memory of thecircuit board 1308.

The digital still camera 1300 also includes a video signal outputterminal 1312 and an input/output terminal 1314 for data communicationson the side of the case 1302. As shown in the drawing, the video signaloutput terminal 1312 is coupled to a television monitor 1430, and theinput/output terminal 1314 is coupled to a personal computer 1440, whenrequired. In this case, the imaging signal stored in the memory of thecircuit board 1308 is output to the television monitor 1430 or thepersonal computer 1440 by a predetermined process.

Examples of electronic apparatuses to which the invention is applied,other than the (mobile) personal computer shown in FIG. 2, the cellularphone shown in FIG. 3 and the digital still camera shown in FIG. 4,include: television sets, video cameras, viewfinder or monitor-viewingvideo tape recorders, laptop personal computers, car navigation systems,pagers, electronic notebooks (including electronic notebooks withcommunication functions), electronic dictionaries, calculators,electronic game machines, word processors, workstations, videophones,security monitors, electronic binoculars, point-of-sales terminals,touch-panel devices (e.g. automatic teller machines of financialinstitutions, automatic ticket machines), medical instruments (e.g.electronic thermometers, sphygmomanometers, blood sugar meters,electrocardiogram displays, ultrasonic diagnosis devices, endoscopedisplays), fish detectors, measuring instruments and gauges (e.g.vehicle, airplane, and marine gauges), flight simulators, monitors,projectors and other projection displays.

While the preferred embodiments of the invention have been described,they are not intended to limit the invention.

For example, the method for manufacturing the metal particle dispersionliquid may include one or more steps for any purpose.

Furthermore, the metal particle dispersion liquid may be manufactured byother methods than any of the above-described methods. For example,while the metal salt is obtained by the reduction reaction with thereducing agent in the above-described embodiments, the reaction may beachieved with ultraviolet rays, electron beams or thermal energy.

Furthermore, the electronic device and apparatus according to any of theabove-described embodiments may include any substitute that has the samefunction as its original member and may include any additional member.

Working Examples

A specific working example according to the invention will now bedescribed.

Method for Manufacturing Silver Dispersion Liquid (Metal ParticleDispersion Liquid)

Sample No. I-1

A solution (mercapto-and-ester-group-containing compound solution) wasprepared by dissolving 1.23-gram n-octylthioglycolate(mercapto-and-ester-group-containing compound) in 100-ml toluene.

Separately, 1.02-gram silver nitrate monohydrate (metal salt) wasdissolved in 20-ml water and was then mixed with another solution inwhich 14.6-gram tetraoctylammonium bromide (phase-transfer catalyst) wasdissolved in 270-ml toluene. The mixture was agitated for 30 minutes atroom temperature. The mercapto-and-ester-group-containing compoundsolution was added to the mixture and then agitated for another 30minutes to obtain a toluene/water two-phase liquid.

Subsequently, another solution was prepared by dissolving 2.28-gramborohydride sodium (reducing agent) in 140-ml water. This solution wasdropped in the toluene/water two-phase liquid that had been wellagitated. The liquid was further agitated for three hours at roomtemperature to obtain a dispersion liquid in which silver particles weredispersed. The liquid was then left for a certain period of time toseparate a toluene phase and a water phase. It was observed that thesilver particles were in the toluene phase, while the water phase wasclear and colorless. After the water phase was separated and removed,740-ml ethanol was added to the toluene phase to make the silverparticles precipitate. The precipitating silver particles were made tothoroughly settle down with a centrifugal machine. Then toluene wasremoved to obtain the silver particles. Subsequently, the silverparticles were dispersed in tetralin to obtain a silver dispersionliquid (metal particle dispersion liquid) with a silver concentration of30 wt %. The diameter of the silver particles in the silver dispersionliquid was measured to be 3.0 nm by dynamic scattering (HPPS byMalvern). Transmission electron microscope (TEM) observation confirmedthat crystalline first particles had been formed.

Sample No. I-2

A silver dispersion liquid was prepared in the same manner as Sample No.I-1, except for using limonene instead of tetralin to disperse silverparticles.

Sample No. I-3

A silver dispersion liquid was prepared in the same manner as Sample No.I-1, except for using alpha-terpineol instead of tetralin to dispersesilver particles.

Sample Nos. I-4, I-5, I-6

Silver dispersion liquids were prepared with Sample Nos. I-4, I-5 andI-6 in the same manner as Sample Nos. I-1, I-2 and I-3, respectively,except for using 0.81-gram 3-mercaptopropionic acid ethyl instead ofn-octylthioglycolate as the mercapto-and-ester-group-containingcompound.

Sample Nos. I-7, I-8, I-9

Silver dispersion liquids were prepared with Sample Nos. 1-7, 1-8 andI-9 in the same manner as Sample Nos. I-1, I-2 and 1-3, respectively,except for using 1.57-gram 6-mercapto caproate n-octyl instead ofn-octylthioglycolate as the mercapto-and-ester-group-containingcompound.

Sample Nos. I-10, I-11, I-12

Silver dispersion liquids were prepared with Sample Nos. I-10, I-11 andI-12 in the same manner as Sample Nos. I-1, I-2 and I-3, respectively,except for using 1.82-gram 8-mercapto caprylate n-nonyl instead ofn-octylthioglycolate as the mercapto-and-ester-group-containingcompound.

Sample No. I-13

A silver dispersion liquid was prepared in the same manner as Sample No.I-1, except for using 1.37-gram caproate n-octyl instead ofn-octylthioglycolate. In this case, since silver particles coagulatedand no dispersion liquid was available.

Sample No. I-14

A silver dispersion liquid was prepared in the same manner as Sample No.I-1, except for using 1.06-gram 8-mercapto caprylate instead ofn-octylthioglycolate.

Sample No. I-15

A silver dispersion liquid was prepared in the same manner as Sample No.I-1, except for using 1.22-gram 1-dodecanethiol instead ofn-octylthioglycolate.

TEM photo data revealed particle size distribution for each of thesamples. The average diameter and peak half width in the sizedistribution were measured. Table 1 shows the conditions and measurementfor each sample silver dispersion liquid.

TABLE 1 Ag particle Dispersing agent Ave. Half Content DispersionContent dia width Molecular [Molar Sample No. medium [wt %] [nm] [nm]Material weight ratio to Ag] I-1 (Invention) Tetralin 30 3 0.5 n- 204 1octylthioglycolate I-2 (Invention) Limonene 30 3.2 0.5 n- 204 1octylthioglycolate I-3 (Invention) Alpha- 30 3.1 0.5 n- 204 1 terpineoloctylthioglycolate I-4 (Invention) Tetralin 30 2.5 0.5 3- 134 1mercaptopropionic acid ethyl I-5 (Invention) Limonene 30 2.8 0.5 3- 1341 mercaptopropionic acid ethyl I-6 (Invention) Alpha- 30 2.6 0.5 3- 1341 terpineol mercaptopropionic acid ethyl I-7 (Invention) Tetralin 10 102 6-mercapto 260 1 caproate n-octyl I-8 (Invention) Limonene 10 13 26-mercapto 260 1 caproate n-octyl I-9 (Invention) Alpha- 10 12 26-mercapto 260 1 terpineol caproate n-octyl I-10 Tetralin 5 25 58-mercapto 302 1 (Invention) caprylate n-nonyl I-11 Limonene 5 30 58-mercapto 302 1 (Invention) caprylate n-nonyl I-12 Alpha- 5 28 58-mercapto 302 1 (Invention) terpineol caprylate n-nonyl I-13 Tetralin —— — caproate n-octyl 228 1 (Comparative) I-14 Tetralin 10 15 38-mercapto 176 1 (Comparative) caprylate I-15 Tetralin 30 5 0.51-dodecanethiol 202 1 (Comparative)

As Table 1 shows, the metal particle dispersion liquids of the samplesaccording to the invention has a small variance in particle diametersand sharp size distribution.

Dispersion Liquid Stability

The samples were left at 20 degrees Celsius for three days. They wasthen classified into the following four classes based on their state ofsilver particle dispersion.

A: A highly dispersed state of the metal particles as a dispersedsubstance was maintained.

B: No silver particle precipitation was observed, but there was someunevenness seemingly attributed to a variance in silver particlediameters in the dispersion liquid.

C: Some silver particle precipitation was observed.

D: Significant silver particle precipitation was observed.

Table 2 shows the classification results.

TABLE 2 Sample No. Dispersion liquid stability I-1 (Invention) A I-2(Invention) A I-3 (Invention) A I-4 (Invention) A I-5 (Invention) A I-6(Invention) A I-7 (Invention) B I-8 (Invention) B I-9 (Invention) B I-10(Invention) C I-11 (Invention) C I-12 (Invention) C I-13 (Comparative) DI-14 (Comparative) D I-15 (Comparative) A

As Table 2 shows, the metal particle dispersion liquids of the samplesaccording to the invention has high dispersion stability of the metalparticles.

Making of Wiring (Conductive Film)

Sample No. II-1

The silver dispersion liquid of Sample No. I-1 was discharged on a glasssubstrate in a line pattern with an inkjet device and dried at 100degrees Celsius to form a film. The same process was repeated to provideanother film on top of the film that had been formed.

Subsequently, the resultant film was burned at 150 degrees Celsius for60 minutes to provide wiring (conductive film) to a line width of 50 μmand a thickness of 1 μm. This burning was carried out by ultravioletradiation with a wavelength of 254 nm and a radiation intensity of 10mW/cm².

Sample Nos. II-2 to II-15

Wiring (conductive films) was provided in the same manner as Sample No.II-1, except for using the silver dispersion liquids of Sample Nos. I-2to I-15 instead of the silver dispersion liquid of Sample No. I-1.

Sample Nos. III-1 to III-15

Wiring (conductive films) was provided in the same manner as Sample Nos.II-1 to II-15, except for burning was carried out at 250 degrees Celsiusfor 10 minutes.

Evaluation of Wiring (Conductive Film)

For each wiring (conductive films) of Sample Nos. II-1 to II-15 and Nos.III-1 to III-15, electrical resistance (resistivity) was measured.

Table 3 shows the measurement results.

TABLE 3 UV (254 nm, UV (254 nm, 10 mW/cm²), burning Electrical 10mW/cm²), burning Electrical at 150 degrees C. resistance at 250 degreesC. resistance for 60 min. (μΩcm) for 10 min. (μΩcm) II-1 (Invention) 90III-1 (Invention) 7 II-2 (Invention) 100 III-2 (Invention) 8 II-3(Invention) 80 III-3 (Invention) 6 II-4 (Invention) 100 III-4(Invention) 8 II-5 (Invention) 110 III-5 (Invention) 9 II-6 (Invention)90 III-6 (Invention) 7 II-7 (Invention) 300 III-7 (Invention) 15 II-8(Invention) 350 III-8 (Invention) 18 II-9 (Invention) 280 III-9(Invention) 13 II-10 (Invention) 650 III-10 (Invention) 30 II-11(Invention) 800 III-11 (Invention) 40 II-12 (Invention) 570 III-12(Invention) 35 II-13 (Comparative) — III-13 (Comparative) — II-14(Comparative) — III-14 (Comparative) 120 II-15 (Comparative) — III-15(Comparative) 85

As Table 2 shows, the wiring (conductive films) of the samples accordingto the invention has low electrical resistance. Furthermore, it ispossible to provide wiring by burning at lower temperatures than thecomparative samples.

Since no dispersion liquid was available with the comparative sampleI-13, no evaluation was made with Sample Nos. II-13 and III-13. This wasbecause they included no thiol functioning as a dispersing agent.

As for the comparative samples II-14 and II-15, no measurement data wereavailable, since no electrical conduction occurred. As for thecomparative samples III-14 and III-15, which involved burning at thehigher temperature, electrical conduction occurred but electricalresistance was larger than the samples according to the invention. Thiswas because the comparative samples I-14 and I-15 has no ester group,thereby ultraviolet radiation to provide wiring (conductive films) hadno effects.

The wiring (conductive films) of Sample Nos. III-1 to III-12 were usedto manufacture electronic devices and apparatuses as shown in FIGS. 1through 4. Accordingly, it was confirmed that efficient and reliableelectronic devices and apparatuses were manufactured.

The above-mentioned results were also available when the same evaluationwas carried out with metal particle dispersion liquids that had beenprepared in the same manner as described above except for using goldparticles or Ag—Pd alloy particles as metal particles.

Another specific working example according to the invention will now bedescribed.

Method for Manufacturing Silver Dispersion Liquid (Metal ParticleDispersion Liquid)

Sample No. IV-1

A solution (heterocyclic compound solution) was prepared by dissolving0.72-gram 2-mercapto-5-methyl-1,3,4-thiadiazole (heterocyclic compound)shown by Chemical Formula 10 below in 100-ml toluene.

Separately, 1.02-gram silver nitrate monohydrate (metal salt) wasdissolved in 20-ml water and was then mixed with another solution inwhich 14.6-gram tetraoctylammonium bromide (phase-transfer catalyst) wasdissolved in 270-ml toluene. The mixture was agitated for 30 minutes atroom temperature. The heterocyclic compound solution was added to themixture and then agitated for another 30 minutes to obtain atoluene/water two-phase liquid.

Subsequently, another solution was prepared by dissolving 2.28-gramborohydride sodium (reducing agent) in 140-ml water. This solution wasdropped in the toluene/water two-phase liquid that had been wellagitated. The liquid was further agitated for three hours at roomtemperature to obtain a dispersion liquid in which silver particles weredispersed. The liquid was then left for a certain period of time toseparate a toluene phase and a water phase. It was observed that thesilver particles were in the toluene phase, while the water phase wasclear and colorless. After the water phase was separated and removed,740-ml ethanol was added to the toluene phase to make the silverparticles precipitate. The precipitating silver particles were made tothoroughly settle down with a centrifugal machine. Then toluene wasremoved to obtain the silver particles. Subsequently, the silverparticles were dispersed in toluene to obtain a silver dispersion liquid(metal particle dispersion liquid) with a silver concentration of 10 wt%. The diameter of the silver particles in the silver dispersion liquidwas measured to be 5.0 nm by dynamic scattering (HPPS by Malvern).Transmission electron microscope (TEM) observation confirmed thatcrystalline first particles had been formed.

Sample Nos. IV-2, IV-3

Silver dispersion liquids were prepared in the same manner as Sample No.IV-1, except for changing the contents of2-mercapto-5-methyl-1,3,4-thiadiazole in the silver dispersion liquid asshown in Table 4.

Sample No. IV-4

A silver dispersion liquid was prepared in the same manner as Sample No.IV-1, except for using 0.65-gram 2-mercaptothiazole shown by ChemicalFormula 11 below instead of 2-mercapto-5-methyl-1,3,4-thiadiazole as theheterocyclic compound.

Sample No. IV-5

A silver dispersion liquid was prepared in the same manner as Sample No.IV-1, except for using 0.55-gram 5-mercapto-1,2,3-triazole shown byChemical Formula 12 below instead of2-mercapto-5-methyl-1,3,4-thiadiazole as the heterocyclic compound.

Sample No. IV-6

A silver dispersion liquid was prepared in the same manner as Sample No.IV-1, except for using no heterocyclic compound (dispersing agent). Inthis case, since silver particles coagulated when the reducing agent wasadded and no dispersion liquid was available.

Sample No. IV-7

A silver dispersion liquid was prepared in the same manner as Sample No.IV-1, except for using 1.1-gram 1-dodecanethiol instead of2-mercapto-5-methyl-1,3,4-thiadiazole.

Sample No. IV-8

A silver dispersion liquid was prepared in the same manner as Sample No.IV-1, except for using 0.52-gram 2,5-dimethylfuran instead of2-mercapto-5-methyl-1,3,4-thiadiazole. In this case, since silverparticles coagulated when the reducing agent was added and no dispersionliquid was available.

TEM photo data revealed particle size distribution for each of thesamples. The average diameter and peak half width in the sizedistribution were measured. Table 4 shows the conditions and measurementfor each sample silver dispersion liquid.

TABLE 4 Ag particle Dispersing agent Ave. Half Content DispersionContent dia width Molecular [Molar Sample No. medium [wt %] [nm] [nm]Material weight ratio to Ag] IV-1 Toluene 10 5 1 2-mercapto-5- 132 1(Invention) methyl-1,3,4- thiadiazole IV-2 Toluene 10 7 2 2-mercapto-5-132 0.1 (Invention) methyl-1,3,4- thiadiazole IV-3 Toluene 10 4.5 12-mercapto-5- 132 2 (Invention) methyl-1,3,4- thiadiazole IV-4 Toluene10 5.5 1 2- 119 1 (Invention) mercaptothiazole IV-5 Toluene 10 8 35-mercapto-1,2,3- 101 1 (Invention) triazole IV-6 — — — — — — —(Comparative) IV-7 Toluene 10 6 1 1-dodecanethiol 202 1 (Comparative)IV-8 — — — — 2,5-dimethylfuran 96 1 (Comparative)

As Table 4 shows, the metal particle dispersion liquids of the samplesaccording to the invention has a small variance in particle diametersand sharp size distribution.

Dispersion Liquid Stability

The samples were left at 20 degrees Celsius for three days. They wasthen classified into the following four classes based on their state ofsilver particle dispersion.

A: A highly dispersed state of the metal particles as a dispersedsubstance was maintained.

B: No silver particle precipitation was observed, but there was someunevenness seemingly attributed to a variance in silver particlediameters in the dispersion liquid.

C: Some silver particle precipitation was observed.

D: Significant silver particle precipitation was observed.

Table 5 shows the classification results.

TABLE 5 Sample No. Dispersion liquid stability IV-1 (Invention) A IV-2(Invention) C IV-3 (Invention) B IV-4 (Invention) A IV-5 (Invention) BIV-6 (Comparative) D IV-7 (Comparative) A IV-8 (Comparative) D

As Table 5 shows, the metal particle dispersion liquids of the samplesaccording to the invention has high dispersion stability of the metalparticles.

Making of Wiring (Conductive Film)

Sample No. V-1

The silver dispersion liquid of Sample No. IV-1 was discharged on aglass substrate in a line pattern with an inkjet device and dried at 110degrees Celsius to form a film. The same process was repeated to provideanother film on top of the film that had been formed.

Subsequently, the resultant film was burned at 150 degrees Celsius for60 minutes to provide wiring (conductive film) to a line width of 50 μmand a thickness of 1 μm. This burning was carried out by ultravioletradiation with a wavelength of 254 nm and a radiation intensity of 10mW/cm².

Sample Nos. V-2 to V-8

Wiring (conductive films) was provided in the same manner as Sample No.V-1, except for using the silver dispersion liquids of Sample Nos. IV-2to IV-8 instead of the silver dispersion liquid of Sample No. IV-1.

Sample Nos. VI-1 to VI-8

Wiring (conductive films) was provided in the same manner as Sample Nos.V-1 to V-8, except for burning was carried out at 250 degrees Celsiusfor 10 minutes.

Evaluation of Wiring (Conductive Film)

For each wiring (conductive films) of Sample Nos. V-1 to V-8 and Nos.VI-1 to VI-8, electrical resistance (resistivity) was measured.

Table 6 shows the measurement results.

TABLE 6 Burning Electrical Burning at 150 degrees C. resistance at 250degrees C. Electrical for 60 min. (μΩcm) for 10 min. resistance (μΩcm)V-1 (Invention) 100 VI-1 (Invention) 8 V-2 (Invention) 120 VI-2(Invention) 10 V-3 (Invention) 250 VI-3 (Invention) 20 V-4 (Invention)90 VI-4 (Invention) 8 V-5 (Invention) 380 VI-5 (Invention) 18 V-6(Comparative) — VI-6 (Comparative) — V-7 (Comparative) — VI-7(Comparative) 85 V-8 (Comparative) — VI-8 (Comparative) — Notexperimented with Sample Nos. V-6, V-8, VI-6 and VI-8, since thedispersion liquid was not available with these samples. No measurementdata available with Sample No. V-7, since no electrical resistanceoccurred under the above burning conditions.

As Table 6 shows, the wiring (conductive films) of the samples accordingto the invention has low electrical resistance. Furthermore, it ispossible to provide wiring by burning at lower temperatures than thecomparative samples.

Since no dispersion liquid was available with the comparative samplesIV-6 and IV-8, no evaluation was made with Sample Nos. V-6, V-8, VI-6and VI-8.

As for the comparative sample V-7, no measurement data were available,since no electrical conduction occurred. As for the comparative samplesVI-7, which involved burning at the higher temperature, electricalconduction occurred but electrical resistance was larger than thesamples according to the invention.

The conductive films of Sample Nos. VI-1 to VI-5 were used tomanufacture electronic devices and apparatuses as shown in FIGS. 1through 4. Accordingly, it was confirmed that efficient and reliableelectronic devices and apparatuses were manufactured.

The above-mentioned results were also available when the same evaluationwas carried out with metal particle dispersion liquids that had beenprepared in the same manner as described above except for using goldparticles or Ag—Pd alloy particles as metal particles.

Yet another specific working example according to the invention will nowbe described.

Method for Manufacturing Silver Dispersion Liquid (Metal ParticleDispersion Liquid)

Sample No. VII-1

A solution (thiol solution) was prepared by dissolving 0.55-gram1-dodecanethiol in 10-ml toluene.

Separately, 5.1-gram silver nitrate monohydrate (metal salt) wasdissolved in 10-ml water and was then mixed with another solution inwhich 19.6-gram tetraoctylammonium bromide (phase-transfer catalyst) wasdissolved in 50-ml toluene. The mixture was agitated for 30 minutes atroom temperature. The thiol solution was added to the mixture and thenagitated for another 30 minutes to obtain a toluene/water two-phaseliquid.

Subsequently, another solution was prepared by dissolving 1.3-gramborohydride sodium (reducing agent) in 200-ml water. This solution wasdropped in the toluene/water two-phase liquid that had been wellagitated. The liquid was further agitated for three hours at roomtemperature to obtain a dispersion liquid in which silver particles weredispersed. It was observed that the silver particles were in the toluenephase, while the water phase was clear and colorless. After the waterphase was separated and removed, the toluene phase was concentrated toone third of its volume. Then, 70-ml ethanol was added to make thesilver particles precipitate. The precipitating silver particles weremade to thoroughly settle down with a centrifugal machine. Then toluenewas removed to obtain the silver particles. Subsequently, the silverparticles were dispersed in tetralin to obtain a silver dispersionliquid (metal particle dispersion liquid) with a silver concentration of30 wt %. The diameter of the silver particles in the silver dispersionliquid was measured to be 2.0 nm by dynamic scattering (HPPS byMalvern). Transmission electron microscope (TEM) observation confirmedthat crystalline first particles had been formed.

Sample Nos. VII-2, VII-3

Silver dispersion liquids were prepared in the same manner as Sample No.VII-1, except for changing conditions to drop the solution ofborohydride sodium (reducing agent) in the toluene/water two-phaseliquid and to agitate the two-phase liquid.

Sample Nos. VII-4 to VII-8

Silver dispersion liquids were prepared in the same manner as Sample No.VII-1, except for changing the volume of 1-dodecanethiol and tetralinsuch that the silver dispersion liquids contain 1-dodecanethiol and thesilver particles as shown in Table 7.

Sample Nos. VII-9 to VII-13

Silver dispersion liquids were prepared in the same manner as Sample No.VII-2, except for changing the volume of 1-dodecanethiol and tetralinsuch that the silver dispersion liquids contain 1-dodecanethiol and thesilver particles as shown in Table 7.

Sample Nos. VII-14 to VII-18

Silver dispersion liquids were prepared in the same manner as Sample No.VII-3, except for changing the volume of 1-dodecanethiol and tetralinsuch that the silver dispersion liquids contain 1-dodecanethiol and thesilver particles as shown in Table 7.

Sample Nos. VII-19 to VII-21

Silver dispersion liquids were prepared with Sample Nos. VII-19 toVII-21 in the same manner as Sample No. VII-1 to VII-3, respectively,except for using 1-octanethiol instead of 1-dodecanethiol.

Sample Nos. VII-22 to VII-24

Silver dispersion liquids were prepared with Sample Nos. VII-19 toVII-21 in the same manner as Sample No. VII-1 to VII-3, respectively,except for using 1-hexanethiol instead of 1-dodecanethiol.

Sample Nos. VII-25 to VII-27

Silver dispersion liquids were prepared with Sample Nos. VII-19 toVII-21 in the same manner as Sample No. VII-1 to VII-3, respectively,except for using 1-icosanethiol instead of 1-dodecanethiol.

Sample No. VII-28

A silver dispersion liquid was prepared in the same manner as Sample No.VII-1, except for using limonene instead of tetralin to disperse silverparticles.

Sample No. VII-29

A silver dispersion liquid was prepared in the same manner as Sample No.VII-1, except for using alpha-terpineol instead of tetralin to dispersesilver particles.

TEM photo data revealed particle size distribution for each of thesamples. The average diameter and peak half width in the sizedistribution were measured. Tables 7 and 8 show the conditions andmeasurement for each sample silver dispersion liquid.

TABLE 7 Silver particle Dispersing agent Ave. Half Content DispersionContent Y dia A width (Molar X lower X upper Sample No. medium [wt %][nm] [nm] Material ratio) X limit to A limit to A VII-1 Tetralin 30 20.5 1- 0.1 0.025 0.5 (Invention) dodecanethiol VII-2 Tetralin 30 10 1 1-0.1 0.005 0.1 (Invention) dodecanethiol VII-3 Tetralin 30 110 10 1- 0.10.0004 0.009 (Comparative) dodecanethiol VII-4 Tetralin 30 2 1 1- 0.020.025 0.5 (Comparative) dodecanethiol VII-5 Tetralin 30 2 0.5 1- 0.05 ↑↑ (Invention) dodecanethiol VII-6 Tetralin 30 2 0.5 1- 0.1 ↑ ↑(Invention) dodecanethiol VII-7 Tetralin 30 2 0.5 1- 0.5 ↑ ↑ (Invention)dodecanethiol VII-8 Tetralin 30 2 0.5 1- 1 ↑ ↑ (Comparative)dodecanethiol VII-9 Tetralin 30 10 6 1- 0.003 0.005 0.1 (Comparative)dodecanethiol VII-10 Tetralin 30 10 3 1- 0.005 ↑ ↑ (Invention)dodecanethiol VII-11 Tetralin 30 10 1 1- 0.01 ↑ ↑ (Invention)dodecanethiol VII-12 Tetralin 30 10 1 1- 0.05 ↑ ↑ (Invention)dodecanethiol VII-13 Tetralin 30 10 1 1- 0.2 ↑ ↑ (Comparative)dodecanethiol VII-14 Tetralin — — — 1- 0.0002 0.0004 0.009 (Comparative)dodecanethiol VII-15 Tetralin 10 110 50 1- 0.001 ↑ ↑ (Comparative)dodecanethiol VII-16 Tetralin 10 110 30 1- 0.002 ↑ ↑ (Comparative)dodecanethiol VII-17 Tetralin 10 110 30 1- 0.005 ↑ ↑ (Comparative)dodecanethiol VII-18 Tetralin 10 110 30 1- 0.02 ↑ ↑ (Comparative)dodecanethiol No dispersion liquid was available with Sample No. VII-14under the above condition, since the particles coagulated soon afterthey had been made.

TABLE 8 Silver particle Dispersing agent Ave. Half Content DispersionContent Y dia A width (Molar X lower X upper Sample No. medium [wt %][nm] [nm] Material ratio) X limit to A limit to A VII-19 Tetralin 30 20.8 1-octanethiol 0.1 0.025 0.5 (Invention) VII-20 Tetralin 30 10 21-octanethiol 0.1 0.005 0.1 (Invention) VII-21 Tetralin 30 110 201-octanethiol 0.1 0.0004 0.009 (Comparative) VII-22 Tetralin — 2 —1-hexanethiol 0.1 0.025 0.5 (Comparative) VII-23 Tetralin — 10 —1-hexanethiol 0.1 0.005 0.1 (Comparative) VII-24 Tetralin — 110 —1-hexanethiol 0.1 0.0004 0.009 (Comparative) VII-25 Tetralin 30 2 11-icosanethiol 0.1 0.025 0.5 (Comparative) VII-26 Tetralin 30 10 31-icosanethiol 0.1 0.005 0.1 (Comparative) VII-27 Tetralin 30 110 301-icosanethiol 0.1 0.0004 0.009 (Comparative) VII-28 Limonene 30 2 0.51- 0.1 0.025 0.5 (Invention) dodecanethiol VII-29 Alpha- 30 2 0.5 1- 0.10.025 0.5 (Invention) terpineol dodecanethiol No dispersion liquid wasavailable with Sample Nos. VII-22, 23 and 24 under the above conditions,since the particles coagulated soon after they had been made.

Dispersion Liquid Stability

The samples were left at 20 degrees Celsius for three days. They wasthen classified into the following four classes based on their state ofsilver particle dispersion.

A: A highly dispersed state of the metal particles as a dispersedsubstance was maintained.

B: No silver particle precipitation was observed, but there was someunevenness seemingly attributed to a variance in silver particlediameters in the dispersion liquid.

C: Some silver particle precipitation was observed.

D: Significant silver particle precipitation was observed.

Table 9 shows the classification results.

TABLE 9 Dispersion liquid Sample No. stability VII-1 (Invention) A VII-2(Invention) A VII-3 (Comparative) C VII-4 (Comparative) D VII-5(Invention) B VII-6 (Invention) A VII-7 (Invention) A VII-8(Comparative) A VII-9 (Comparative) D VII-10 (Invention) B VII-11(Invention) A VII-12 (Invention) A VII-13 (Comparative) A VII-14(Comparative) D VII-15 (Comparative) D VII-16 (Comparative) C VII-17(Comparative) C VII-18 (Comparative) B VII-19 (Invention) B VII-20(Invention) B VII-21 (Comparative) C VII-22 (Comparative) D VII-23(Comparative) D VII-24 (Comparative) D VII-25 (Comparative) B VII-26(Comparative) B VII-27 (Comparative) B VII-28 (Invention) A VII-29(Invention) A

As Table 9 shows, the metal particle dispersion liquids of the samplesaccording to the invention has high dispersion stability of the metalparticles.

Making of Wiring (Conductive Film)

Sample No. VIII-1

The silver dispersion liquid of Sample No. VII-1 was discharged on aglass substrate in a line pattern with an inkjet device and dried at 110degrees Celsius to form a film. The same process was repeated to provideanother film on top of the film that had been formed.

Subsequently, the resultant film was burned at 150 degrees Celsius for60 minutes to provide wiring (conductive film) to a line width of 50 μmand a thickness of 1 μm. This burning was carried out by ultravioletradiation with a wavelength of 254 nm and a radiation intensity of 10mW/cm².

Sample Nos. VIII-2 to VIII-29

Wiring (conductive films) was provided in the same manner as Sample No.VIII-1, except for using the silver dispersion liquids of Sample Nos.VII-2 to VII-29 instead of the silver dispersion liquid of Sample No.VII-1.

Sample Nos. IX-1 to IX-29

Wiring (conductive films) was provided in the same manner as Sample Nos.VIII-1 to VIII-29, except for burning was carried out at 250 degreesCelsius for 10 minutes.

Evaluation of Wiring (Conductive Film)

For each wiring (conductive films) of Sample Nos. VIII-1 to VIII-29 andNos. IX-1 to IX-29, electrical resistance (resistivity) was measured.

Table 10 shows the measurement results.

TABLE 10 Burning Electrical Burning Electrical at 150 degrees C.resistance at 250 degrees C. resistance for 60 min. (μΩcm) for 10 min.(μΩcm) VIII-1 (Invention) 100 IX-1 (Invention) 7 VIII-2 (Invention) 120IX-2 (Invention) 9 VIII-3 (Comparative) 250 IX-3 (Comparative) 30 VIII-4(Comparative) 200 IX-4 (Comparative) 20 VIII-5 (Invention) 180 IX-5(Invention) 12 VIII-6 (Invention) 100 IX-6 (Invention) 7 VIII-7(Invention) 130 IX-7 (Invention) 10 VIII-8 (Comparative) 800 IX-8(Comparative) 25 VIII-9 (Comparative) 300 IX-9 (Comparative) 30 VIII-10(Invention) 140 IX-10 (Invention) 10 VIII-11 (Invention) 80 IX-11(Invention) 6 VIII-12 (Invention) 90 IX-12 (Invention) 7 VIII-13(Comparative) 280 IX-13 (Comparative) 20 VIII-14 (Comparative) — IX-14(Comparative) — VIII-15 (Comparative) — IX-15 (Comparative) — VIII-16(Comparative) — IX-16 (Comparative) — VIII-17 (Comparative) — IX-17(Comparative) — VIII-18 (Comparative) — IX-18 (Comparative) — VIII-19(Invention) 160 IX-19 (Invention) 12 VIII-20 (Invention) 180 IX-20(Invention) 13 VIII-21 (Comparative) 500 IX-21 (Comparative) 45 VIII-22(Comparative) — IX-22 (Comparative) — VIII-23 (Comparative) — IX-23(Comparative) — VIII-24 (Comparative) — IX-24 (Comparative) — VIII-25(Comparative) 1200 IX-25 (Comparative) 40 VIII-26 (Comparative) 1800IX-26 (Comparative) 45 VIII-27 (Comparative) 2500 IX-27 (Comparative) 60VIII-28 (Invention) 100 IX-28 (Invention) 7 VIII-29 (Invention) 110IX-29 (Invention) 8 Poor dispersion with Sample Nos. VIII-14, 15, 16, 17and 18 and IX-14, 15, 16, 17 and 18 resulted in inkjet clogs. Nodispersion liquid was available with Sample Nos. VIII-22, 23 and 24 andIX-22, 23 and 24.

As Table 10 shows, the wiring (conductive films) of the samplesaccording to the invention has low electrical resistance. Furthermore,it is possible to provide wiring by burning at lower temperatures thanthe comparative samples. As for the wiring (conductive films) of thecomparative samples, electrical resistance was larger than the samplesaccording to the invention.

The conductive films of Sample Nos. VIII-1 to VIII-29 (except for thecomparative samples) were used to manufacture electronic devices andapparatuses as shown in FIGS. 1 through 4. Accordingly, it was confirmedthat efficient and reliable electronic devices and apparatuses weremanufactured.

The above-mentioned results were also available when the same evaluationwas carried out with metal particle dispersion liquids that had beenprepared in the same manner as described above except for using goldparticles or Ag—Pd alloy particles as metal particles.

Still another specific working example according to the invention willnow be described.

Method for Manufacturing Silver Dispersion Liquid (Metal ParticleDispersion Liquid)

Sample No. X-1

A solution (dispersing-agent/beta-ketoester solution) was prepared bydissolving 1.2-gram 1-dodecanethiol (dispersing agent) and 4.8-gram4,4,4-trifluoroacetoacetic acid isopropyl (beta-ketoester) in 10-mltoluene.

Separately, 5.1-gram silver nitrate monohydrate (metal salt) wasdissolved in 10-ml water and was then mixed with another solution inwhich 19.6-gram tetraoctylammonium bromide (phase-transfer catalyst) wasdissolved in 50-ml toluene. The mixture was agitated for 30 minutes atroom temperature. The dispersing-agent/beta-ketoester solution was addedto the mixture and then agitated for another 30 minutes to obtain atoluene/water two-phase liquid.

Subsequently, another solution was prepared by dissolving 1.3-gramborohydride sodium (reducing agent) in 200-ml water. This solution wasdropped in the toluene/water two-phase liquid that had been wellagitated. The liquid was further agitated for three hours at roomtemperature to obtain a dispersion liquid in which silver particles weredispersed. The liquid was then left for a certain period of time toseparate a toluene phase and a water phase. It was observed that thesilver particles were in the toluene phase, while the water phase wasclear and colorless. After the water phase was separated and removed,the toluene phase was concentrated to one third of its volume. Then,70-ml ethanol was added to make the silver particles precipitate. Theprecipitating silver particles were made to thoroughly settle down witha centrifugal machine. Then toluene was removed to obtain the silverparticles. Subsequently, the silver particles were dispersed in tetralinto obtain a silver dispersion liquid (metal particle dispersion liquid)with a silver concentration of 30 wt %. The diameter of the silverparticles in the silver dispersion liquid was measured to be 5 nm bydynamic scattering (HPPS by Malvern). Transmission electron microscope(TEM) observation confirmed that crystalline first particles had beenformed.

Sample No. X-2

A silver dispersion liquid was prepared in the same manner as Sample No.X-1, except for using limonene instead of tetralin to disperse silverparticles.

Sample No. X-3

A silver dispersion liquid was prepared in the same manner as Sample No.X-1, except for using alpha-terpineol instead of tetralin to dispersesilver particles.

Sample Nos. X-4, X-5

Silver dispersion liquids were prepared in the same manner as Sample No.X-1, except for changing the contents of 4,4,4-trifluoroacetoacetic acidisopropyl (beta-ketoester) in the silver dispersion liquid as shown inTable 11.

Sample Nos. X-6, X-7, X-8

Silver dispersion liquids were prepared with Sample Nos. X-6, X-7 andX-8 in the same manner as Sample Nos. X-1, X-2 and X-3, respectively,except for using 3.2-gram ethyl acetoacetate instead of4,4,4-trifluoroacetoacetic acid isopropyl as the beta-ketoester.

Sample Nos. X-9, X-10, X-11

Silver dispersion liquids were prepared with Sample Nos. with SampleNos. X-9, X-10 and X-11 in the same manner as Sample Nos. X-1, X-2 andX-3, respectively, except for using 0.87-gram 1-octanethiol instead of1-dodecanethiol as the dispersing agent.

Sample No. X-12

A silver dispersion liquid was prepared in the same manner as Sample No.X-1, except for using no 1-dodecanethiol.

Sample No. X-13

A silver dispersion liquid was prepared in the same manner as Sample No.X-1, except for using no 4,4,4-trifluoroacetoacetic acid isopropyl.

TEM photo data revealed particle size distribution for each of thesamples. The average diameter and peak half width in the sizedistribution were measured. Table 11 shows the conditions andmeasurement for each sample silver dispersion liquid.

TABLE 11 Ag particle Dispersing agent Beta-ketoester Ave. Half MolarMolar Sample Dispersion Content dia width Molecular ratio Molecularratio No. medium [wt %] [nm] [nm] Material weight to Ag Material weightto Ag X-1 Tetralin 30 5 0.5 1- 202 0.25 4,4,4- 198 1 (Invention)dodecane trifluoroacetoacetic thiol acid isopropyl X-2 Limonene 30 5.40.5 1- 202 0.25 4,4,4- 198 1 (Invention) dodecane trifluoroacetoaceticthiol acid isopropyl X-3 Alpha- 30 5.2 0.5 1- 202 0.25 4,4,4- 198 1(Invention) terpineol dodecane trifluoroacetoacetic thiol acid isopropylX-4 Tetralin 30 4.8 0.5 1- 202 0.25 4,4,4- 198 0.4 (Invention) dodecanetrifluoroacetoacetic thiol acid isopropyl X-5 Tetralin 30 7 2 1- 2020.25 4,4,4- 198 0.1 (Invention) dodecane trifluoroacetoacetic thiol acidisopropyl X-6 Tetralin 30 9 3 1- 202 0.25 Ethyl 130 1 (Invention)dodecane acetoacetate thiol X-7 Limonene 30 12 4 1- 202 0.25 Ethyl 130 1(Invention) dodecane acetoacetate thiol X-8 Alpha- 30 10 3 1- 202 0.25Ethyl 130 1 (Invention) terpineol dodecane acetoacetate thiol X-9Tetralin 10 20 5 1- 146 0.25 4,4,4- 198 1 (Invention) octanethioltrifluoroacetoacetic acid isopropyl X-10 Limonene 10 25 7 1- 146 0.254,4,4- 198 1 (Invention) octanethiol trifluoroacetoacetic acid isopropylX-11 Alpha- 10 23 7 1- 146 0.25 4,4,4- 198 1 (Invention) terpineoloctanethiol trifluoroacetoacetic acid isopropyl X-12 Tetralin 5 30 10 —— — 4,4,4- 198 1 (Comparative) trifluoroacetoacetic acid isopropyl X-13Tetralin 5 10 3 1- 202 0.25 — — — (Comparative) dodecane thiol

As Table 11 shows, the metal particle dispersion liquids of the samplesaccording to the invention has a small variance in particle diametersand sharp size distribution.

Dispersion Liquid Stability

The samples were left at 20 degrees Celsius for three days. They wasthen classified into the following four classes based on their state ofsilver particle dispersion.

A: A highly dispersed state of the metal particles as a dispersedsubstance was maintained.

B: No silver particle precipitation was observed, but there was someunevenness seemingly attributed to a variance in silver particlediameters in the dispersion liquid.

C: Some silver particle precipitation was observed.

D: Significant silver particle precipitation was observed.

Table 12 shows the classification results.

TABLE 12 Sample No. Dispersion liquid stability X-1 (Invention) A X-2(Invention) A X-3 (Invention) A X-4 (Invention) A X-5 (Invention) B X-6(Invention) B X-7 (Invention) B X-8 (Invention) B X-9 (Invention) C X-10(Invention) C X-11 (Invention) C X-12 (Comparative) D X-13 (Comparative)C

As Table 12 shows, the metal particle dispersion liquids of the samplesaccording to the invention has high dispersion stability of the metalparticles.

Making of Wiring (Conductive Film)

Sample No. XI-1

The silver dispersion liquid of Sample No. X-1 was discharged on a glasssubstrate in a line pattern with an inkjet device and dried at 110degrees Celsius to form a film. The same process was repeated to provideanother film on top of the film that had been formed.

Subsequently, the resultant film was burned at 150 degrees Celsius for60 minutes to provide wiring (conductive film) to a line width of 50 μmand a thickness of 1 μm. This burning was carried out by ultravioletradiation with a wavelength of 254 nm and a radiation intensity of 10mW/cm².

Sample Nos. XI-2 to XI-13

Wiring (conductive films) was provided in the same manner as Sample No.XI-1, except for using the silver dispersion liquids of Sample Nos. X-2to X-13 instead of the silver dispersion liquid of Sample No. X-1.

Sample Nos. XII-1 to XII-13

Wiring (conductive films) was provided in the same manner as Sample Nos.XI-1 to XI-13, except for burning was carried out at 250 degrees Celsiusfor 10 minutes.

Evaluation of Wiring (Conductive Film)

For each wiring (conductive films) of Sample Nos. XII-1 to XII-13,electrical resistance (resistivity) was measured.

Table 13 shows the measurement results.

TABLE 13 Burning at Electrical Burning at Electrical 150 degrees C.resistance 250 degrees C. resistance for 60 min. (μΩcm) for 10 min.(μΩcm) XI-1 (Invention) 120 XII-1 (Invention) 10 XI-2 (Invention) 150XII-2 (Invention) 12 XI-3 (Invention) 140 XII-3 (Invention) 11 XI-4(Invention) 100 XII-4 (Invention) 8 XI-5 (Invention) 200 XII-5(Invention) 15 XI-6 (Invention) 500 XII-6 (Invention) 30 XI-7(Invention) 1000 XII-7 (Invention) 40 XI-8 (Invention) 800 XII-8(Invention) 35 XI-9 (Invention) 160 XII-9 (Invention) 13 XI-10(Invention) 200 XII-10 (Invention) 16 XI-11 (Invention) 180 XII-11(Invention) 14 XI-12 (Comparative) 4000 XII-12 (Comparative) 80 XI-13(Comparative) 3500 XII-13 (Comparative) 50

As Table 13 shows, the wiring (conductive films) of the samplesaccording to the invention has low electrical resistance. Furthermore,it is possible to provide wiring by burning at lower temperatures thanthe comparative samples.

As for the wiring (conductive films) of the comparative samples,electrical resistance was definitely larger than the samples accordingto the invention.

The conductive films of Sample Nos. XI-1 to XI-11 were used tomanufacture electronic devices and apparatuses as shown in FIGS. 1through 4. Accordingly, it was confirmed that efficient and reliableelectronic devices and apparatuses were manufactured by low-temperatureprocessing.

The above-mentioned results were also available when the same evaluationwas carried out with metal particle dispersion liquids that had beenprepared in the same manner as described above except for using goldparticles or Ag—Pd alloy particles as metal particles.

1. A metal particle dispersion liquid, comprising: a metal particle; acompound including a sulfur atom; and a dispersion medium, the compoundbeing disposed at a surface of the metal particle.
 2. The metal particledispersion liquid according to claim 1, a diameter range of the metalparticle being 1 to 100 nm.
 3. The metal particle dispersion liquidaccording to claim 1, further comprising a dispersion aid.
 4. The metalparticle dispersion liquid according to claim 1, the compound coveringthe metal particle.
 5. The metal particle dispersion liquid according toclaim 1, the metal particle including one of Ag, Au, Pt, Pd, Ru, Rh, Os,Ir, Cu, Al, Ni, Sn and Mg.
 6. The metal particle dispersion liquidaccording to claim 5, a ratio of the one of Ag, Au, Pt, Pd, Ru, Rh, Os,Ir, Cu, Al, Ni, Sn and Mg to the metal particle being 90 wt % or more.7. The metal particle dispersion liquid according to claim 3, thedispersion aid including beta-ketoester.